WO2022097572A1 - Dispersant for suspension polymerization and method for producing vinyl-based polymer - Google Patents

Dispersant for suspension polymerization and method for producing vinyl-based polymer Download PDF

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WO2022097572A1
WO2022097572A1 PCT/JP2021/039941 JP2021039941W WO2022097572A1 WO 2022097572 A1 WO2022097572 A1 WO 2022097572A1 JP 2021039941 W JP2021039941 W JP 2021039941W WO 2022097572 A1 WO2022097572 A1 WO 2022097572A1
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pva
dispersant
vinyl
formula
polymerization
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PCT/JP2021/039941
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French (fr)
Japanese (ja)
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美鈴 藤森
雅己 加藤
達也 谷田
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株式会社クラレ
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Priority to US18/251,593 priority Critical patent/US20230406964A1/en
Priority to DE112021005800.2T priority patent/DE112021005800T5/en
Priority to CN202180074555.9A priority patent/CN116438208A/en
Priority to JP2022560748A priority patent/JP7321394B2/en
Publication of WO2022097572A1 publication Critical patent/WO2022097572A1/en

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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F2/00—Processes of polymerisation
    • C08F2/12—Polymerisation in non-solvents
    • C08F2/16—Aqueous medium
    • C08F2/20—Aqueous medium with the aid of macromolecular dispersing agents
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F14/00—Homopolymers and copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen
    • C08F14/02—Monomers containing chlorine
    • C08F14/04—Monomers containing two carbon atoms
    • C08F14/06—Vinyl chloride
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F16/00—Homopolymers and copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an alcohol, ether, aldehydo, ketonic, acetal or ketal radical
    • C08F16/02—Homopolymers and copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an alcohol, ether, aldehydo, ketonic, acetal or ketal radical by an alcohol radical
    • C08F16/04—Acyclic compounds
    • C08F16/06—Polyvinyl alcohol ; Vinyl alcohol
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F2/00—Processes of polymerisation
    • C08F2/38—Polymerisation using regulators, e.g. chain terminating agents, e.g. telomerisation
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F8/00—Chemical modification by after-treatment
    • C08F8/12—Hydrolysis
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K5/00—Use of organic ingredients
    • C08K5/04—Oxygen-containing compounds
    • C08K5/10—Esters; Ether-esters
    • C08K5/12—Esters; Ether-esters of cyclic polycarboxylic acids

Definitions

  • the present invention relates to a dispersant for suspension polymerization and a method for producing a vinyl polymer.
  • Vinyl alcohol-based polymers (hereinafter, may be abbreviated as "PVA") are generally used as a dispersant for suspension polymerization of vinyl-based compounds.
  • PVA Vinyl alcohol-based polymers
  • a vinyl-based compound dispersed in an aqueous medium is polymerized using an oil-soluble catalyst to obtain a particulate vinyl-based polymer.
  • a dispersant is added to the aqueous medium for the purpose of improving the quality of the obtained polymer.
  • Factors controlling the quality of the vinyl polymer obtained by suspension polymerization of the vinyl compound include the polymerization rate, the ratio of water to the vinyl compound (monomer), the polymerization temperature, the type of oil-soluble catalyst, and the factors.
  • the type of the polymerization vessel There are the amount, the type of the polymerization vessel, the stirring speed of the contents in the polymerization vessel, the type of the dispersant, and the like. Among them, the type of dispersant has a great influence on the quality such as the particle size distribution of the vinyl polymer or the absorbability of the plasticizer.
  • PVA is used as a dispersant alone or in combination with different types of PVA or cellulose derivatives such as methyl cellulose and carboxymethyl cellulose.
  • the average degree of polymerization is 500 or more
  • the ratio (Pw / Pn) of the weight average degree of polymerization Pw to the number average degree of polymerization Pn is 3.0 or less
  • a carbonyl group and a vinylene group adjacent thereto are present.
  • the present invention provides a dispersant for suspension polymerization and a vinyl-based polymer, which can obtain polymer particles having a small average particle size, a small number of coarse particles, and good plasticizer absorption even when the amount used is small. It is an object of the present invention to provide the manufacturing method of.
  • a dispersant for suspension polymerization having a structure represented by the following formula (1) and containing a vinyl alcohol-based polymer satisfying the following formula (2); 0.4 ⁇ [X] x 10 2 / [ Ra, 1 ] 2 ⁇ 3.0 (2)
  • R is a hydrocarbon group having 4 or more carbon atoms.
  • [X] is the content (mol%) of the structure represented by the formula (1) with respect to all the structural units of the vinyl alcohol polymer, and [ Ra, 1 ] is the above. It is the HSP distance ((J / cm 3 ) 1/2 ) between the structure represented by the formula (1) and vinyl chloride.
  • [4] A dispersant for suspension polymerization according to any one of [1] to [3], wherein the vinyl alcohol polymer satisfies the following formula (3); 3.5 ⁇ [X] x 10 5 / [ Ra, 2 ] 2 ⁇ 25 (3)
  • the definition of [X] is the same as that of the formula (2)
  • [ Ra, 2 ] is the HSP distance between the structure represented by the formula (1) and water ((J / J /). cm 3 ) 1/2 ).
  • any method for producing a vinyl-based polymer comprising a step of suspend-polymerizing a vinyl-based compound in the presence of the dispersant for suspension polymerization according to any one of [1] to [4]. Achieved by doing.
  • a dispersant for suspension polymerization and a vinyl-based dispersant capable of obtaining polymer particles having a small average particle size, a small number of coarse particles, and good plasticizer absorbability even when the amount used is small.
  • a method for producing a polymer can be provided.
  • the dispersant for suspension polymerization of the present invention contains a vinyl alcohol-based polymer (PVA).
  • the PVA is a polymer having a vinyl alcohol unit as a structural unit.
  • the PVA has a structure represented by the following formula (1).
  • the structure represented by the formula (1) is usually located at the end of PVA.
  • R is a hydrocarbon group having 4 or more carbon atoms.
  • the number of carbon atoms in R is less than 4, polymer particles having a small average particle size and a small number of coarse particles cannot be obtained when the amount of the dispersant used is small.
  • the PVA can be obtained by polymerizing vinyl acetate using, for example, an aldehyde having 5 or more carbon atoms as a chain transfer agent and then saponifying the vinyl acetate.
  • an aldehyde having 3 or 4 carbon atoms is used, the PVA can be obtained. , It is difficult to separate unreacted aldehyde and vinyl acetate, and it is difficult to reuse vinyl acetate.
  • the PVA in the formula (1) having an R of 4 or more is excellent in production efficiency.
  • the lower limit of the carbon number of R is preferably 5 and may be more preferably 6.
  • the upper limit of the number of carbon atoms of R is preferably 12, more preferably 10, and even more preferably 8.
  • the upper limit of the carbon number of R is the above value, it is easier to obtain polymer particles having a small average particle diameter and few coarse particles, and the availability of raw materials is excellent, so that the polymer particles can be produced at low cost.
  • the hydrocarbon group represented by R may be an aromatic hydrocarbon group such as a phenyl group or an aliphatic hydrocarbon group, but is preferably an aliphatic hydrocarbon group.
  • the aliphatic hydrocarbon group include a chain aliphatic hydrocarbon group such as an alkyl group, an alkenyl group and an alkynyl group, and a cyclic aliphatic hydrocarbon group such as a cycloalkyl group, a cycloalkenyl group and a cycloalkynyl group.
  • chain aliphatic hydrocarbon groups are preferred.
  • the chain aliphatic hydrocarbon group may be a linear group or a branched group.
  • the aliphatic hydrocarbon group may be a saturated aliphatic hydrocarbon group such as an alkyl group or an unsaturated aliphatic hydrocarbon group such as an alkenyl group, but the saturated aliphatic hydrocarbon group may be used.
  • the hydrocarbon group represented by R an alkyl group is more preferable, and a linear alkyl group is further preferable.
  • the alkyl group represented by R include a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group and the like.
  • the PVA satisfies the following formula (2). 0.4 ⁇ [X] x 10 2 / [ Ra, 1 ] 2 ⁇ 3.0 (2)
  • [X] is the content rate (mol%) of the structure represented by the formula (1) with respect to all the structural units of the PVA.
  • [ Ra, 1 ] is the HSP distance ((J / cm 3 ) 1/2 ) between the structure represented by the formula (1) and vinyl chloride.
  • the dispersant of the present invention can stabilize the polymerization of the vinyl compound even when the amount used is small, which is caused by the unstable polymerization. It exerts an excellent effect of reducing blocking. As a result, polymer particles having a small average particle diameter, few coarse particles, and high plasticizer absorbability can be obtained.
  • the lower limit of [X] ⁇ 10 2 / [ Ra, 1 ] 2 is preferably 0.5, more preferably 0.6, still more preferably 0.7, and 0.8, 0.9 or 0.95. It may be preferable.
  • the upper limit of [X] ⁇ 10 2 / [ Ra, 1 ] 2 is preferably 2.9, more preferably 2.8, further preferably 2.7, and preferably 2.6 or 2.5. There is also.
  • the lower limit of the content rate [X] of the structure represented by the formula (1) with respect to all the structural units of PVA is preferably 0.01 mol%, more preferably 0.03 mol%, and further preferably 0.05 mol%. Preferably, 0.07 mol%, 0.08 mol%, 0.09 mol% or 0.10 mol% may be even more preferable.
  • the upper limit of the above [X] is preferably 3 mol%, more preferably 2 mol%, 1.5 mol%, 1.2 mol%, 1.0 mol%, 0.8 mol%, 0.6. More preferably, mol%, 0.5 mol% or 0.4 mol%.
  • the plasticizer absorbability of the polymer particles obtained by suspension polymerization tends to be excellent.
  • the above [X] can be calculated by 1 H-NMR analysis of PVA resaponified to a saponification degree of 99.5 mol%. More specifically, it can be calculated by the method described in Examples.
  • the lower limit of the HSP distance [ Ra, 1 ] between the structure represented by the formula (1) and vinyl chloride is preferably 1 (J / cm 3 ) 1/2 , and 2 (J / cm 3 ) 1/2 . More preferably, 2.5 (J / cm 3 ) 1/2 or 2.8 (J / cm 3 ) 1/2 may be even more preferred.
  • the upper limit of the HSP distance [ Ra, 1 ] between the structure represented by the formula (1) and vinyl chloride is preferably 5.5 (J / cm 3 ) 1/2 , and 4.9 (J / cm). 3 ) 1/2 is more preferred, 4.5 (J / cm 3 ) 1/2 , 4.2 (J / cm 3 ) 1/2 , 4.0 (J / cm 3 ) 1/2 or 3.
  • the HSP distance [ Ra, 1 ] between the structure represented by the formula (1) and vinyl chloride is described in Hideki Yamamoto, "SP Value: Basics, Applications and Calculation Methods” (published in 2005, Information Organization) and J. Mol. It can be calculated by the method described in "POLYMER HANDBOOK” (published in 2003, Wiley) by Brandrup. Further, the structure represented by the formula (1) in PVA can be calculated by 1 H-NMR analysis of PVA resaponified to a saponification degree of 99.5 mol%, and the details are described by the method described in Examples. Can be calculated.
  • the HSP distance between two substances is a parameter corresponding to the distance between two points when the value of the HSP value ( ⁇ d, ⁇ p, ⁇ h) is considered as the coordinates of the three-dimensional space.
  • the HSP value is represented by three components, a dispersion term ( ⁇ d), a polarity term ( ⁇ p) and a hydrogen bond term ( ⁇ h).
  • ⁇ d, ⁇ p and ⁇ h of this structure are the molar volumes of the structure represented by the following formula (4).
  • V) can be obtained by the following formula (5) and then by the following formulas (6) to (8).
  • m in the following formula (5) is a number of 3 or more, because 1 measurement error in 1 H-NMR analysis, when a structure represented by a plurality of types of formula (1) is introduced in PVA, etc. , Does not have to be an integer.
  • Hideki Yamamoto's "SP Value: Basics / Applications and Calculation Methods” (2005) is based on the following method. Published in the year, Information Organization) and J.M. It can be calculated by the method described in "POLYMER HANDBOOK" (published in 2003, Wiley) by Brandrup.
  • the HSP distance [ Ra, 1 ] can be obtained by the following equation (9) using these values.
  • [R a, 1 ] ⁇ 4 ( ⁇ D 1 - ⁇ d) 2 + ( ⁇ P 1 - ⁇ p) 2 + ( ⁇ H 1 - ⁇ h) 2 ⁇ 1/2 (9)
  • the PVA preferably satisfies the following formula (3). 3.5 ⁇ [X] x 10 5 / [ Ra, 2 ] 2 ⁇ 25 (3)
  • [X] is the content rate (mol%) of the structure represented by the formula (1) with respect to all the structural units of the PVA.
  • [ Ra, 2 ] is the HSP distance ((J / cm 3 ) 1/2 ) between the structure represented by the equation (1) and water.
  • the lower limit of [X] ⁇ 10 5 / [ Ra, 2 ] 2 is preferably 4, more preferably 6, and even more preferably 7, 8, 9 or 10.
  • the upper limit of [X] ⁇ 105 / [ Ra, 2 ] 2 is preferably 22 is preferable, 20 is more preferable, and 18, 16 or 15 may be further preferable. It is considered that [X] ⁇ 10 5 / [ Ra, 2 ] 2 can represent the degree of compatibility between PVA and water.
  • the upper limit of the HSP distance [ Ra, 2 ] between the structure represented by the formula (1) and water is preferably 45 (J / cm 3 ) 1/2 , more preferably 42 (J / cm 3 ) 1/2 . It may be preferable.
  • the lower limit of the HSP distance [ Ra, 2 ] between the structure represented by the formula (1) and water is preferably 36 (J / cm 3 ) 1/2 .
  • the HSP distance [ Ra, 2 ] between the structure represented by the equation (1) and water is described in Hideki Yamamoto, "SP Value: Basics, Applications and Calculation Methods” (published in 2005, Information Organization) and J. Mol. It can be calculated by the method described in "POLYMER HANDBOOK” (published in 2003, Wiley) by Brandrup. Specifically, it can be calculated by the same method as the above-mentioned HSP distance [ Ra, 1 ]. That is, the HSP distance [ Ra, 2 ] is determined from the HSP values ( ⁇ d, ⁇ p, ⁇ h) of the structure represented by the equation (1) and the HSP values ( ⁇ D 2 , ⁇ P 2 , ⁇ H 2 ) of water. It can be obtained by the following formula (10).
  • the PVA is obtained by polymerizing a vinyl ester in the presence of an aldehyde having 5 or more carbon atoms and saponifying the obtained vinyl ester-based polymer, as will be described in detail later.
  • the lower limit of the saponification degree of PVA 20 mol% is preferable, 30 mol% is more preferable, and 40 mol% may be further preferable.
  • the upper limit of the degree of saponification may be 100 mol%, but 99.5 mol% is preferable, 99.2 mol% is more preferable, 99 mol% is further preferable, and 95 mol% or 90 mol% is preferable. It may be preferable.
  • the lower limit of the saponification degree of the PVA is preferably 60 mol%, more preferably 65 mol%, still more preferably 68 mol%.
  • the upper limit of the saponification degree of the PVA is preferably 80 mol%, more preferably 70 mol%, and even more preferably 60 mol%.
  • the primary dispersant is an additive used for enhancing the dispersibility of the monomer during suspension polymerization and controlling the particle size of the obtained polymer particles.
  • the secondary dispersant is an additive usually used together with the primary dispersant in order to increase the porosity of the obtained polymer particles.
  • the saponification degree is a value measured by the method described in JIS K 6726: 1994.
  • the lower limit of the viscosity average degree of polymerization of PVA 100 is preferable, 120 is more preferable, 150 is further preferable, 160 is further preferable, and 200, 300, 400, 500 or 600 may be further preferable.
  • the viscosity average degree of polymerization is at least the above lower limit, the protective colloidal property is enhanced, and various performances as a dispersant such as polymerization stability are further enhanced.
  • the upper limit of the viscosity average degree of polymerization is preferably 5,000, more preferably 3,500, still more preferably 2,000, and even more preferably 1,500, 1,000 or 800.
  • the viscosity average degree of polymerization is not more than the above upper limit, the surface active performance is enhanced and various performances as a dispersant are further improved.
  • the lower limit of the viscosity average degree of polymerization of PVA is preferably 200, more preferably 300, still more preferably 400, still more preferably 500, and particularly preferably 600. ..
  • the upper limit of the viscosity average degree of polymerization of PVA is preferably 800, more preferably 700, and even more preferably 600.
  • the viscosity average degree of polymerization of PVA is a value measured according to JIS K 6726: 1994.
  • the structure represented by the formula (12) is formed, for example, by heat-treating a PVA having the structure represented by the formula (1).
  • the PVA has the structure represented by the formula (12)
  • the absorbance is at least the lower limit
  • the structure represented by the formula (12) is sufficiently formed in PVA, and polymer particles having a smaller average particle diameter and fewer coarse particles can be obtained. Therefore, in such a case, even when the amount used is particularly small, polymer particles having a small average particle diameter, a small number of coarse particles, and good plasticizer absorbability can be obtained.
  • the upper limit of the absorbance of the 0.1 mass% aqueous solution of PVA at an optical path length of 10 mm and a wavelength of 320 nm is preferably 0.4, more preferably 0.35, and even more preferably 0.30 or 0.25. .. If the structure represented by the formula (12) is excessively formed in the PVA, it may affect the plasticizer absorbability of the obtained polymer particles. Therefore, when the absorbance is not more than the upper limit, the plasticizer absorbability of the obtained polymer particles can be enhanced.
  • the content thereof is preferably 3.5 mmol% or less, more preferably 3.0 mmol% or less, based on the total structural units of the PVA. 5 mmol% or less may be more preferred.
  • the lower limit of the content is not particularly limited, and it does not have to have a formyl group at the terminal substantially.
  • various performances as a dispersant may be improved, and in particular, the plasticizer absorbability of the obtained polymer particles may be improved.
  • the content of the formyl group at the terminal of PVA tends to increase when the polymerization is carried out in a system to which oxygen is supplied.
  • the degree of polymerization of PVA also affects the content of formyl groups at the ends.
  • the content of the formyl group can be calculated by performing 1 H-NMR measurement in a state where the PVA is washed with methanol or the like and unreacted aldehyde or the like is removed.
  • the PVA may have a structure represented by the formula (1) and a structural unit other than the structural unit (vinyl alcohol unit and vinyl ester unit) derived from vinyl ester.
  • the monomer giving the other structural unit include ⁇ -olefins such as ethylene, propylene, n-butene, and isobutylene; acrylic acid and salts thereof; methyl acrylate, ethyl acrylate, n-propyl acrylate, and acrylic.
  • Acrylic acid esters such as i-propyl acid, n-butyl acrylate, i-butyl acrylate, t-butyl acrylate, 2-ethylhexyl acrylate, dodecyl acrylate, octadecyl acrylate; methacrylic acid and salts thereof; methacrylic acid Methyl, ethyl methacrylate, n-propyl methacrylate, i-propyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, t-butyl methacrylate, 2-ethylhexyl methacrylate, dodecyl methacrylate, octadecyl methacrylate, etc.
  • Acrylic acid ester acrylamide; N-methylacrylamide, N-ethylacrylamide, N, N-dimethylacrylamide, diacetoneacrylamide, acrylamide propanesulfonic acid and its salts, acrylamidepropyldimethylamine and its salts or quaternary salts thereof, N -Acrylamide derivatives such as methylolacrylamide and its derivatives; methacrylicamide; N-methylmethacrylicamide, N-ethylmethacrylicamide, methacrylicamide propanesulfonic acid and its salts, methacrylicamidepropyldimethylamine and its salts or quaternary salts thereof, N -Methylamide derivatives such as methylolmethacrylicamide and its derivatives; methylvinyl ether, ethylvinyl ether, n-propylvinyl ether, i-propylvinyl ether, n-butylvinyl ether, i-butylvin
  • Vinyl ether nitriles such as acrylic nitrile and methacrylonitrile
  • vinyl halides such as vinyl chloride and vinyl fluoride
  • vinylidene halides such as vinylidene chloride and vinylidene fluoride
  • allyl compounds such as allyl acetate and allyl chloride
  • maleic acid and itacone examples thereof include unsaturated dicarboxylic acids such as acids and fumaric acids and salts thereof or mono or dialkyl esters thereof; vinylsilyl compounds such as vinyltrimethoxysilane; isopropenyl acetate, 3,4-diacetoxy-1-butene and the like.
  • the other monomer one kind or two or more kinds can be used.
  • the ratio of the other structural units to the total structural units in the PVA may be preferably 20 mol% or less, more preferably 10 mol% or less, and further preferably 5 mol%, 3 mol% or 1 mol%. It may be preferable. On the other hand, the ratio of the other structural units may be, for example, 0.1 mol% or more, and may be 1 mol% or more.
  • the method for producing PVA contained in the dispersant of the present invention is not particularly limited, but for example, a vinyl ester-based polymer obtained by polymerizing a vinyl ester monomer by adding an aldehyde having 5 or more carbon atoms as a modifier is added. There is a method to polymerize.
  • an alkyl aldehyde is preferable, and for example, a linear alkyl aldehyde such as 1-pentanal, 1-hexanal, 1-heptanal, 1-octanal, 1-nonanal, 1-decanal, 1-undecanal; 7- Linear alkenyl aldehydes such as octanal; branched alkyl aldehydes such as 2-methylbutanal, 2-ethylhexanal, 2-ethylbutanal and 2-methylundecanal can be mentioned.
  • the aldehyde may be used alone or in combination of two or more.
  • the aldehyde acts as a chain transfer agent, and PVA having the structure represented by the formula (1) can be easily produced.
  • the amount of the aldehyde used is not particularly limited, but is preferably 0.5 parts by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the vinyl ester monomer.
  • the aldehyde usually acts as a chain transfer agent.
  • a chain transfer agent other than the aldehyde may be used in combination.
  • Other chain transfer agents include, for example, aldehydes other than the above aldehydes (eg, acetaldehyde, 1-propanol, 1-butanal); ketones such as acetone, methyl ethyl ketone, hexanone, cyclohexanone; mercaptans such as 2-hydroxyethanethiol; 3 -Thiocarboxylic acids such as mercaptopropionic acid and thioacetic acid; halogenated hydrocarbons such as trichlorethylene and perchloroethylene can be mentioned.
  • the amount of the chain transfer agent added may be determined according to the chain transfer constant of the chain transfer agent, the degree of polymerization of PVA to be achieved, and the like.
  • Examples of the method for polymerizing the vinyl ester monomer include a bulk polymerization method, a solution polymerization method, a suspension polymerization method, an emulsion polymerization method, a dispersion polymerization method, and the like, and from an industrial point of view, a solution polymerization method, an emulsion polymerization method, or the like.
  • the dispersion polymerization method is preferable.
  • the polymerization of the vinyl ester monomer may be carried out by any of a batch method, a semi-batch method and a continuous method.
  • the vinyl ester monomer examples include vinyl acetate, vinyl formate, vinyl propionate, vinyl caprylate, vinyl versatic acid and the like, and among these, vinyl acetate is preferable from an industrial point of view.
  • the PVA may be a homopolymer of one kind of vinyl ester monomer or a copolymer of different vinyl ester monomers.
  • the polymerization initiator used for the polymerization is selected from known polymerization initiators such as azo-based initiators, peroxide-based initiators, and redox-based initiators according to the polymerization method.
  • the azo-based initiator is, for example, 2,2'-azobisisobutyronitrile, 2,2'-azobis (2,4-dimethylvaleronitrile), 2,2'-azobis (4-methoxy-2,4). -Dimethylvaleronitrile) and the like.
  • the peroxide peroxide-based initiator is a peroxydicarbonate-based compound such as diisopropylperoxydicarbonate, di (2-ethylhexyl) peroxydicarbonate, diethoxyethylperoxydicarbonate; t-butylperoxyneodecanate, ⁇ -c.
  • Perester compounds such as milperoxyneodecanate; acetylcyclohexylsulfonyl peroxides; 2,4,4-trimethylpentyl-2-peroxyphenoxyacetate and the like.
  • Potassium persulfate, ammonium persulfate, hydrogen peroxide and the like may be combined with the initiator to obtain a polymerization initiator.
  • the redox-based initiator is, for example, the above-mentioned peroxide-based initiator or oxidizing agent (potassium persulfate, ammonium persulfate, hydrogen peroxide solution, etc.), sodium bisulfite, sodium hydrogencarbonate, tartrate acid, L-ascorbic acid, longalit. It is a polymerization initiator in combination with a reducing agent such as.
  • the amount of the polymerization initiator used varies depending on the polymerization catalyst and cannot be unconditionally determined, but is selected according to the polymerization rate.
  • the PVA may be a saponified vinyl ester copolymer obtained by copolymerizing a vinyl ester monomer with another copolymerizable unsaturated monomer to the extent that the gist of the present invention is not impaired. good.
  • the other monomer include the monomers giving the other structural units described above.
  • the PVA copolymer izes unsaturated carboxylic acids, unsaturated dicarboxylic acids, salts thereof, or unsaturated monomers such as mono or dialkyl esters thereof together with vinyl ester monomers for the purpose of improving water solubility.
  • the vinyl ester-based copolymer that has been subjected to the above may be saponified to produce the copolymer.
  • PVA produced using alkylthiol as a chain transfer agent has low water solubility, and it is necessary to take measures such as copolymerizing the unsaturated carboxylic acids and the like, and using an organic solvent such as methanol when preparing an aqueous solution. Often becomes.
  • PVA having the structure represented by the formula (1) and satisfying the formula (2) is relatively highly water-soluble even when it has a hydrocarbon chain having the same carbon number as the alkyl thiol. Therefore, it is not always necessary to take the above-mentioned measures, and the present invention is excellent in this respect as well.
  • an alcoholic decomposition or hydrolysis reaction using a known basic catalyst such as sodium hydroxide, potassium hydroxide or sodium methoxyd or an acidic catalyst such as p-toluenesulfonic acid is carried out. Applicable.
  • Examples of the solvent used for the saponification reaction include alcohols such as methanol and ethanol; esters such as methyl acetate and ethyl acetate; ketones such as acetone and methyl ethyl ketone; aromatic hydrocarbons such as benzene and toluene, and these are one type. May be used alone or in combination of two or more. Above all, it is convenient and preferable to carry out the saponification reaction in the presence of sodium hydroxide as a basic catalyst using methanol or a mixed solution of methanol and methyl acetate as a solvent.
  • a step of cleaning the resin solid matter containing PVA, a step of drying the resin solid matter containing PVA, a step of heat-treating the resin solid matter containing PVA, and the like may be further provided.
  • the treatment temperature for heat treatment can be, for example, 100 ° C. or higher and 150 ° C. or lower.
  • the processing time can be, for example, 10 minutes or more and 3 hours or less.
  • the dispersant of the present invention contains the PVA and may further contain other components.
  • the lower limit of the content of the PVA in the non-volatile content of the dispersant of the present invention is preferably 30% by mass, more preferably 50% by mass, and even more preferably 70% by mass, 90% by mass or 99% by mass. ..
  • the upper limit of the content of the PVA in the non-volatile content of the dispersant of the present invention may be 100% by mass.
  • the non-volatile components other than PVA that may be contained in the dispersant of the present invention include PVA other than PVA, resins other than PVA, surfactants, additives such as plasticizers, and compounds used at the time of production. Can be mentioned.
  • the lower limit of the content of all PVA in the non-volatile content of the dispersant of the present invention is preferably 50% by mass, more preferably 70% by mass, and even more preferably 80% by mass, 90% by mass or 99% by mass. be.
  • the upper limit of the content of all PVA in the non-volatile content of the dispersant of the present invention may be 100% by mass.
  • the content of the volatile content in the dispersant of the present invention is usually 20% by mass or less, preferably 15% by mass or less, and more preferably 10% by mass or less. Examples of the volatile matter that can be contained in the dispersant of the present invention include alcohol, water and the like. That is, the dispersant of the present invention may be substantially composed of the PVA of the present invention.
  • the shape of the dispersant of the present invention is not particularly limited, but it is usually a powder.
  • the dispersant of the present invention may be either a primary dispersant (also referred to as a main dispersant or a dispersion stabilizer) or a secondary dispersant (also referred to as a dispersion aid).
  • a primary dispersant also referred to as a main dispersant or a dispersion stabilizer
  • a secondary dispersant also referred to as a dispersion aid
  • the dispersant of the present invention is suitable as a dispersant for suspension polymerization of vinyl compounds.
  • the dispersant of the present invention By using the dispersant of the present invention, the polymerization stability is enhanced, and polymer particles having a small average particle size and few coarse particles can be efficiently obtained. Further, the polymer particles obtained by suspension polymerization using the dispersant of the present invention tend to have good plasticizer absorbability.
  • the dispersant of the present invention has a small average particle size, few coarse particles, and good plasticizer absorbency even when the amount used is small, for example, 1,500 ppm or 1,000 ppm or less with respect to the monomer. Combined particles can be obtained.
  • the dispersant of the present invention may contain additives such as preservatives, fungicides, antiblocking agents and antifoaming agents usually used for suspension polymerization, if necessary.
  • the content of such additives is usually 1.0% by mass or less.
  • the additive one type may be used alone, or two or more types may be used in combination.
  • the method for producing a vinyl polymer of the present invention comprises a step of suspend-polymerizing a vinyl-based compound in the presence of the dispersant of the present invention.
  • the vinyl-based monomer include vinyl halides such as vinyl chloride; vinyl ester monomers such as vinyl acetate and vinyl propionate; (meth) acrylic acid esters and salts thereof; maleic acid, fumaric acid, and esters thereof. And anhydrides; styrene, acrylonitrile, vinylidene chloride, vinyl ether and the like. Of these, it is preferable to carry out suspension polymerization of vinyl chloride alone or with a monomer capable of copolymerizing with vinyl chloride.
  • Examples of the monomer that can be copolymerized with vinyl chloride include vinyl ester monomers such as vinyl acetate and vinyl propionate; and (meth) acrylic acid esters such as methyl (meth) acrylate and ethyl (meth) acrylate. ⁇ -olefins such as ethylene and propylene; unsaturated dicarboxylic acids such as maleic anhydride and itaconic acid; acrylonitrile, styrene, vinylidene chloride, vinyl ether and the like.
  • An aqueous medium is preferable as the medium used for the suspension polymerization.
  • the aqueous medium include water or one containing water and an organic solvent.
  • the content of water in the aqueous medium is preferably 90% by mass or more.
  • the mass ratio of the aqueous medium to the vinyl compound (aqueous medium / vinyl compound) at the time of suspension polymerization is usually 0.1 to 10, preferably 0.5 to 5, and more preferably 0.9 to 2. ..
  • the amount of the dispersant of the present invention used in the suspension polymerization is not particularly limited, but is preferably 100 ppm or more and 50,000 ppm or less, more preferably 200 ppm or more and 20,000 ppm or less, based on the mass of the vinyl compound. In some cases, 3,000 ppm or less, 5,000 ppm or less, 2,000 ppm or less, or 1,500 ppm or less may be more preferable.
  • the dispersant of the present invention may be used alone, but water-soluble cellulose ethers such as methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose and hydroxypropyl methyl cellulose; water-soluble polymers such as polyvinyl alcohol and gelatin; sorbitan monolaurate and sorbitan. Oil-soluble emulsifiers such as triolate, glycerin tristearate, ethylene oxide propylene oxide block copolymer; can also be used with water-soluble emulsifiers such as polyoxyethylene sorbitan monolaurate, polyoxyethylene glycerin oleate, sodium laurate and the like. These may be used alone or in combination of two or more.
  • an oil-soluble or water-soluble polymerization initiator that has been conventionally used for polymerization of vinyl chloride monomers and the like can be used.
  • the oil-soluble polymerization initiator include peroxydicarbonate compounds such as diisopropylperoxydicarbonate, di (2-ethylhexyl) peroxydicarbonate, and diethoxyethylperoxydicarbonate; t-butylperoxyneodecanate and t-butyl.
  • Perester compounds such as peroxypivalate, t-hexyl peroxypivalate, ⁇ -cumylperoxyneodecanate; acetylcyclohexylsulfonyl peroxide, 2,4,4-trimethylpentyl-2-peroxyphenoxyacetate, 3,5,5 -Peroxides such as trimethylhexanoyl peroxide and lauroyl peroxide; azo compounds such as azobis-2,4-dimethylvaleronitrile and azobis (4-2,4-dimethylvaleronitrile) can be mentioned.
  • water-soluble polymerization initiator examples include potassium persulfate, ammonium persulfate, hydrogen peroxide, cumene hydroperoxide and the like. These oil-soluble or water-soluble polymerization initiators may be used alone or in combination of two or more.
  • additives can be added to the polymerization reaction system as needed.
  • the additive include polymerization inhibitors such as aldehydes, halogenated hydrocarbons and mercaptans, and polymerization inhibitors such as phenol compounds, sulfur compounds and N-oxide compounds.
  • a pH adjuster, a cross-linking agent and the like can be arbitrarily added.
  • the polymerization temperature is not particularly limited, and may be a low temperature of about 20 ° C. or a high temperature of over 90 ° C. Further, in order to increase the heat removal efficiency of the polymerization reaction system, it is also one of the preferable embodiments to use a polymerizer with a reflux capacitor.
  • the mass ratio of the amount of the primary dispersant (for example, the dispersant of the present invention) and the secondary dispersant (for example, the dispersant of the present invention) added (primary dispersant / secondary dispersion).
  • the agent varies depending on the type of dispersant used and the like, but is preferably in the range of 95/5 to 20/80, more preferably in the range of 90/10 to 30/70.
  • the primary dispersant and the secondary dispersant may be added collectively at the initial stage of the polymerization, or may be added separately in the middle of the polymerization.
  • HSP distance (synthesis examples 1 to 11, 17 to 19)
  • the HSP distance [R a, 1 ] ((J / cm 3 ) 1/2 ) and the HSP distance [R a, 2 ] ((J / cm 3 ) 1/2 ) were calculated by the following methods.
  • PVA was re-saponified to a saponification degree of 99.5 mol% or more, and then washed with methanol.
  • methanol Using the obtained 1% by mass D2O solution of PVA (with 0.1% by mass trimethylsilylpropanoic acid added as an internal standard) as a sample, 1 H - NMR measurement was performed (400 MHz, 80 ° C., total 256 times). ).
  • the structure represented by the following formula (4) is formed as the structure represented by the above formula (1).
  • m in the formula (4) is obtained by the following formula (13) from the result of 1 H-NMR measurement.
  • -(C O)-(CH 2 ) m -CH 3 (4)
  • m ⁇ (integral value of peak (a)) ⁇ 3 ⁇ / ⁇ (integral value of peak (b)) ⁇ 2 ⁇ + 2 (13)
  • the peak (a) represents a peak derived from methylene of the alkyl chain existing between 1.22 and 1.38 ppm
  • the peak (b) is between 0.80 and 0.92 ppm.
  • HSP distance (synthesis examples 12, 13: reference value)
  • 1-hexene was used as a denaturing agent in Synthetic Example 12
  • 1-decene was used as a denaturing agent in Synthetic Example 13.
  • the PVA obtained at this time has an alkyl group in the side chain.
  • the HSP distance [R b ] between the alkyl group and vinyl chloride or water was used as a reference value. Specifically, R b was calculated by the following method. 1 1 H-NMR measurement was carried out by the same method as above.
  • n in the structure represented by the following formula (14) derived from the denaturing agent introduced into PVA is obtained by the following formula (15).
  • n ⁇ (integral value of peak (c) / 2) / ⁇ integral value of peak (d) ⁇ / 3 ⁇
  • the peak (c) represents a peak existing between 1.1 and 1.3 ppm
  • the peak (d) represents a peak existing between 0.80 and 0.92 ppm.
  • the HSP distance was calculated.
  • the molar volume of the structure represented by the formula (14) can be calculated by the following formula (16), and the HSP value can be calculated by the following formulas (17) to (19).
  • HSP distance (synthesis examples 14, 15: reference value)
  • 1-octanethiol was used as a denaturing agent in Synthesis Example 14
  • 1-hexanethiol was used as a denaturing agent in Synthesis Example 15.
  • the PVA obtained at this time has an alkylthiol group at the terminal.
  • the HSP distance between the alkylthiol group and vinyl chloride or water was described by Hideki Yamamoto, "SP Value: Basics, Applications and Calculation Methods" (2005, Information Organization) and J. Mol. It was calculated as a reference value in the same manner as the above-mentioned method based on the method described in "POLYMER HANDBOOK" (published in 2003, Wiley) by Brandrup.
  • [Denaturation rate] The content (mol%) of the unit modified by the modifying agent with respect to all the structural units of PVA is referred to as "modification rate".
  • the modification rate is the content of the structure represented by the formula (1) with respect to all the structural units of the vinyl alcohol polymer. It is synonymous with X] (mol%).
  • 1 1 H-NMR measurement was performed and the denaturation rate (mol%) was calculated.
  • PVA was re-saponified to a saponification degree of 99.5 mol% or more, and then washed with methanol.
  • the peak derived from the methyl group contained in the structure derived from the modifier exists at 0.80 to 0.92 ppm when the modifier is, for example, a linear alkylaldehyde having 4 or more carbon atoms.
  • Degeneration rate (mol%) ⁇ ([O] / (3 ⁇ q)) / [M] ⁇ ⁇ 100 (21)
  • the solid content concentration at the time of stopping the polymerization was 51.2% by mass and the polymerization rate was 50%. Subsequently, the unreacted monomer was removed by occasionally adding methanol at 30 ° C. under reduced pressure to obtain a methanol solution (concentration: 34.5% by mass) of the vinyl ester polymer. Next, a 10% methanol solution of sodium hydroxide was added to 174.6 parts by mass (60 parts by mass of the polymer in the solution) of a vinyl ester-based polymer prepared by further adding methanol to this methanol solution. 7 parts by mass, 20 parts by mass of methyl acetate and 2.0 parts by mass of ion-exchanged water were added and saponified at 40 ° C.
  • the polymer concentration of the saponified solution was 30% by mass, the vinyl acetate unit in the polymer.
  • the molar ratio of sodium hydroxide to 0.013, the water content of the saponification solution was 1% by mass).
  • About 12 minutes after adding the methanol solution of sodium hydroxide a gel-like substance was formed, which was pulverized with a pulverizer. After further allowing it to stand at 40 ° C. for 1 hour to promote saponification, 160 parts by mass of methyl acetate and 40 parts by mass of methanol were added, and the mixture was left to wash at 40 ° C. for 30 minutes. After repeating this washing operation twice, the white solid obtained by deliquessing was vacuum dried at 40 ° C.
  • PVA-1 The physical characteristics of PVA-1 are shown in Table 2.
  • PVA-1 was thoroughly washed with methyl acetate using a Soxhlet extractor and vacuum dried at 40 ° C. for 16 hours. After washing, 1 H-NMR measurement was performed using a 1% by mass DMSO solution of PVA-1 (added 0.05% by volume tetramethylsilane as an internal standard) as a sample (400 MHz, 80 ° C., total 256 times). .. Based on this result, the content of formyl groups in PVA-1 with respect to all structural units was determined and found to be 3.0 mmol% or less.
  • the temperature of the reactor was started to rise, and when the internal temperature reached 60 ° C., 0.75 parts by mass of 2,2'-azobisisobutyronitrile (AIBN) was added to start polymerization.
  • AIBN 2,2'-azobisisobutyronitrile
  • the 1-octanethiol methanol solution was added dropwise to the reactor, and the polymerization was carried out at 60 ° C. for 2 hours while keeping the monomer composition ratio in the polymerization solution constant, and then cooled to terminate the polymerization.
  • the solid content concentration at the time of stopping the polymerization was 39.4% by mass, and the polymerization rate was 40%.
  • the amount of 1-octanethiol added was 2.05 parts by mass including the initially charged amount.
  • the unreacted monomer was removed by occasionally adding methanol at 30 ° C. under reduced pressure to obtain a methanol solution (concentration: 38.2% by mass) of the vinyl ester polymer.
  • a 10% methanol solution of sodium hydroxide was added to 175.8 parts by mass (60 parts by mass of the polymer in the solution) of a vinyl ester-based polymer prepared by further adding methanol to this methanol solution.
  • 5 parts by mass, 20 parts by mass of methyl acetate and 2.0 parts by mass of ion-exchanged water were added and saponified at 40 ° C. (25% by mass of the polymer concentration in the saponification solution, vinyl acetate unit in the polymer).
  • the molar ratio of sodium hydroxide to 0.0075, the water content of the saponification solution was 1% by mass).
  • a gel-like substance was formed about 10 minutes after the addition of the methanol solution of sodium hydroxide.
  • the gel was crushed with a crusher and left at 40 ° C. for 1 hour to promote saponification, and then 160 mass of methyl acetate.
  • a portion and 40 parts by mass of methanol were added, and the mixture was washed at 40 ° C. for 30 minutes. After repeating this washing operation twice, the white solid obtained by deliquessing was vacuum dried at 40 ° C. for 16 hours to obtain PVA (PVA-14).
  • the physical characteristics of PVA-14 are shown in Table 2.
  • PVA-15 Polymerization conditions such as the amount of vinyl acetate and methanol charged, the type and amount of modifier added; the saponification conditions such as the concentration of the vinyl ester polymer at the time of saponification and the molar ratio of sodium hydroxide to vinyl acetate units are shown in Table 1.
  • PVA (PVA-15) was produced by the same method as in Synthesis Example 14, except that the changes were made as shown in.
  • the physical characteristics of PVA-15 are shown in Table 2.
  • PVA-16 Polymerization conditions such as the amount of vinyl acetate and methanol charged, the use of no modifier, etc .; the saponification conditions such as the concentration of the vinyl ester polymer at the time of saponification and the molar ratio of sodium hydroxide to vinyl acetate units are shown in Table 1.
  • PVA (PVA-16) was produced by the same method as in Synthesis Example 1 except that it was modified as shown.
  • the physical characteristics of PVA-16 are shown in Table 2.
  • Example 1 Using the obtained PVA-1 as a dispersant for suspension polymerization, suspension polymerization of vinyl chloride was carried out by the following method. Next, the obtained vinyl chloride polymer particles were evaluated for average particle size, coarse particle amount, and plasticizer absorbability. The evaluation results are shown in Table 3.
  • Plasticizer absorbency Weigh a 5 mL syringe filled with 0.02 g of cotton wool (referred to as A (g)), put 0.5 g of vinyl chloride polymer particles into it, and weigh it (referred to as B (g)). After 1 g of dioctylphthalate (DOP) was added and allowed to stand for 15 minutes, the mixture was centrifuged at 3000 rpm for 40 minutes and weighed (referred to as C (g)). Then, the plasticizer absorbability (%) was determined by the following formula (22). It is shown that the higher the plasticizer absorbency, the easier the processing and the less likely it is that defects such as lumps occur in the appearance when the sheet is processed.
  • DOP dioctylphthalate
  • Plasticizer absorbency (%) 100 ⁇ [ ⁇ (CA) / (BA) ⁇ -1] (22)
  • the average particle size of the obtained vinyl chloride particles was small, the number of coarse particles was small, and the polymerization stability was good. Had. In addition, all of the obtained vinyl chloride particles had good plasticizer absorbability.
  • the plasticizer absorbability of Example 9 using the heat-treated PVA-9 is not so high, but the plasticizer absorbability can be improved by reducing the amount of the dispersant used. Since the polymerization stability of PVA-9 is extremely high, the average particle size can be kept sufficiently small even if the amount used is reduced.
  • Example 1 and Example 9 which differ only in the presence or absence of heat treatment for PVA
  • the polymerization stability of Example 9 using the heat-treated PVA-9 is remarkably improved.
  • Comparative Example 7 and Comparative Example 8 are similarly different only in the presence or absence of heat treatment for PVA
  • the improvement effect by the heat treatment is small.
  • the polymerization stability is remarkably improved by heat-treating PVA having the structure represented by the formula (1) and satisfying the formula (2).
  • [X] ⁇ 10 2 / [R a, 1 ] 2 (parameter A of the modification rate and the HSP distance)
  • [X] ⁇ 10 5 / [R a, 2 ] 2 denaturation rate.
  • Example 10 using PVA-10 having a relatively small parameter B) between and HSP distance the result was that the polymerization stability was slightly low. It can be seen that the polymerization stability is further enhanced by using PVA in which these parameters are appropriately adjusted.
  • the dispersant for suspension polymerization of the present invention can be used as a dispersant or the like during suspension polymerization of vinyl compounds.

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Abstract

Provided are: a dispersant for suspension polymerization which, even when used in a small amount, can give polymer particles that have a small average particle diameter and a low coarse-particle content and that satisfactorily absorb plasticizers; and a method for producing a vinyl-based polymer. The dispersant for suspension polymerization includes a vinyl-alcohol-based polymer having a structure represented by formula (1) and satisfying relationship (2). In formula (1), R is a hydrocarbon group having 4 or more carbon atoms. In relationship (2), [X] is the content (mol%) of the structure represented by formula (1) with respect to all the structural units of the vinyl-alcohol-based polymer and [Ra,1] is the HSP distance ((J/cm3)1/2) between the structure represented by formula (1) and vinyl chloride. Relationship (2): 0.4≤[X]×102/[Ra,1]2≤3.0

Description

懸濁重合用分散剤及びビニル系重合体の製造方法Dispersant for Suspension Polymerization and Method for Producing Vinyl Polymer
　本発明は、懸濁重合用分散剤及びビニル系重合体の製造方法に関する。 The present invention relates to a dispersant for suspension polymerization and a method for producing a vinyl polymer.
　ビニルアルコール系重合体（以下、「ＰＶＡ」と略記することがある）は、ビニル系化合物の懸濁重合用分散剤として一般的に用いられている。懸濁重合においては、水性媒体中に分散させたビニル系化合物を油溶性の触媒を用いて重合させることにより、粒子状のビニル系重合体が得られる。その際、得られる重合体の品質向上を目的として、分散剤が水性媒体に添加される。ビニル系化合物を懸濁重合して得られるビニル系重合体の品質を支配する因子には、重合率、水とビニル系化合物（単量体）との比、重合温度、油溶性触媒の種類及び量、重合容器の形式、重合容器における内容物の撹拌速度、分散剤の種類などがある。なかでも分散剤の種類が、ビニル重合体の粒度分布又は可塑剤吸収性といった品質に大きな影響を与える。ＰＶＡは、一種を単独で、又は異なる種類のＰＶＡ若しくはメチルセルロース、カルボキシメチルセルロースなどのセルロース誘導体等と組み合わされて、分散剤として使用されている。 Vinyl alcohol-based polymers (hereinafter, may be abbreviated as "PVA") are generally used as a dispersant for suspension polymerization of vinyl-based compounds. In suspension polymerization, a vinyl-based compound dispersed in an aqueous medium is polymerized using an oil-soluble catalyst to obtain a particulate vinyl-based polymer. At that time, a dispersant is added to the aqueous medium for the purpose of improving the quality of the obtained polymer. Factors controlling the quality of the vinyl polymer obtained by suspension polymerization of the vinyl compound include the polymerization rate, the ratio of water to the vinyl compound (monomer), the polymerization temperature, the type of oil-soluble catalyst, and the factors. There are the amount, the type of the polymerization vessel, the stirring speed of the contents in the polymerization vessel, the type of the dispersant, and the like. Among them, the type of dispersant has a great influence on the quality such as the particle size distribution of the vinyl polymer or the absorbability of the plasticizer. PVA is used as a dispersant alone or in combination with different types of PVA or cellulose derivatives such as methyl cellulose and carboxymethyl cellulose.
　例えば特許文献１には、平均重合度が５００以上、重量平均重合度Ｐｗと数平均重合度Ｐｎとの比（Ｐｗ／Ｐｎ）が３．０以下であり、カルボニル基とこれに隣接するビニレン基とを含む構造［－ＣＯ－（ＣＨ＝ＣＨ）２－］とを有し、０．１％水溶液の波長２８０ｎｍ及び３２０ｎｍでの吸光度が各々０．３以上及び０．１５以上であり、かつ波長２８０ｎｍでの吸光度（ａ）に対する波長３２０ｎｍでの吸光度（ｂ）の比（ｂ）／（ａ）が０．３０以上のＰＶＡからなる分散剤が開示されている。 For example, in Patent Document 1, the average degree of polymerization is 500 or more, the ratio (Pw / Pn) of the weight average degree of polymerization Pw to the number average degree of polymerization Pn is 3.0 or less, and a carbonyl group and a vinylene group adjacent thereto are present. It has a structure [-CO- (CH = CH) 2- ] including, and the absorbance of the 0.1% aqueous solution at wavelengths of 280 nm and 320 nm is 0.3 or more and 0.15 or more, respectively, and the wavelength is A dispersant comprising PVA having a ratio (b) / (a) of the absorbance (b) at a wavelength of 320 nm to the absorbance (a) at 280 nm of 0.30 or more is disclosed.
特公平５－８８２５１号公報Tokusho 5-88251 Gazette
　本発明は、使用量が少ない場合にも、平均粒子径が小さくかつ粗大粒子が少なく、可塑剤吸収性が良好な重合体粒子を得ることができる懸濁重合用分散剤、及びビニル系重合体の製造方法を提供することを目的とする。 The present invention provides a dispersant for suspension polymerization and a vinyl-based polymer, which can obtain polymer particles having a small average particle size, a small number of coarse particles, and good plasticizer absorption even when the amount used is small. It is an object of the present invention to provide the manufacturing method of.
　前記目的は、
［１］下記式（１）で表される構造を有し、下記式（２）を満たすビニルアルコール系重合体を含有する、懸濁重合用分散剤；
Figure JPOXMLDOC01-appb-C000002
 　０．４≦［Ｘ］×１０２／［Ｒａ，１］２≦３．０　　　（２）
　前記式（１）中、Ｒは炭素数４以上の炭化水素基である。
　前記式（２）中、［Ｘ］は前記ビニルアルコール系重合体の全構造単位に対する前記式（１）で表される構造の含有率（モル％）であり、［Ｒａ，１］は前記式（１）で表される構造と塩化ビニルとのＨＳＰ距離（（Ｊ／ｃｍ３）１／２）である。
［２］前記ビニルアルコール系重合体のけん化度が６０モル％以上９９．５モル％以下である、［１］の懸濁重合用分散剤；
［３］前記ビニルアルコール系重合体の粘度平均重合度が１５０以上５，０００以下である、［１］又は［２］の懸濁重合用分散剤；
［４］前記ビニルアルコール系重合体が下記式（３）を満たす、［１］～［３］のいずれかの懸濁重合用分散剤；
　３．５≦［Ｘ］×１０５／［Ｒａ，２］２≦２５　　　（３）
　前記式（３）中、［Ｘ］の定義は前記式（２）と同じであり、［Ｒａ，２］は前記式（１）で表される構造と水とのＨＳＰ距離（（Ｊ／ｃｍ３）１／２）である。
［５］［１］～［４］のいずれかの懸濁重合用分散剤の存在下で、ビニル系化合物の懸濁重合を行う工程を備える、ビニル系重合体の製造方法
のいずれかを提供することにより達成される。 The purpose is
[1] A dispersant for suspension polymerization having a structure represented by the following formula (1) and containing a vinyl alcohol-based polymer satisfying the following formula (2);
Figure JPOXMLDOC01-appb-C000002
 0.4 ≤ [X] x 10 2 / [ Ra, 1 ] 2 ≤ 3.0 (2)
In the formula (1), R is a hydrocarbon group having 4 or more carbon atoms.
In the formula (2), [X] is the content (mol%) of the structure represented by the formula (1) with respect to all the structural units of the vinyl alcohol polymer, and [ Ra, 1 ] is the above. It is the HSP distance ((J / cm 3 ) 1/2 ) between the structure represented by the formula (1) and vinyl chloride.
[2] The dispersant for suspension polymerization according to [1], wherein the vinyl alcohol-based polymer has a saponification degree of 60 mol% or more and 99.5 mol% or less.
[3] The dispersant for suspension polymerization according to [1] or [2], wherein the vinyl alcohol-based polymer has a viscosity average degree of polymerization of 150 or more and 5,000 or less.
[4] A dispersant for suspension polymerization according to any one of [1] to [3], wherein the vinyl alcohol polymer satisfies the following formula (3);
3.5 ≤ [X] x 10 5 / [ Ra, 2 ] 2 ≤ 25 (3)
In the formula (3), the definition of [X] is the same as that of the formula (2), and [ Ra, 2 ] is the HSP distance between the structure represented by the formula (1) and water ((J / J /). cm 3 ) 1/2 ).
[5] Provided is any method for producing a vinyl-based polymer, comprising a step of suspend-polymerizing a vinyl-based compound in the presence of the dispersant for suspension polymerization according to any one of [1] to [4]. Achieved by doing.
　本発明によれば、使用量が少ない場合にも、平均粒子径が小さくかつ粗大粒子が少なく、可塑剤吸収性が良好な重合体粒子を得ることができる懸濁重合用分散剤、及びビニル系重合体の製造方法を提供することができる。 According to the present invention, a dispersant for suspension polymerization and a vinyl-based dispersant capable of obtaining polymer particles having a small average particle size, a small number of coarse particles, and good plasticizer absorbability even when the amount used is small. A method for producing a polymer can be provided.
　以下、本発明を実施するための実施形態について説明する。なお、本明細書において、数値範囲（各成分の含有量、各成分から算出される値及び物性など）の上限値及び下限値は適宜組み合わせ可能である。 Hereinafter, embodiments for carrying out the present invention will be described. In the present specification, the upper limit value and the lower limit value of the numerical range (content of each component, value calculated from each component, physical properties, etc.) can be appropriately combined.
＜懸濁重合用分散剤＞
　本発明の懸濁重合用分散剤（以下「分散剤」と称することがある）は、ビニルアルコール系重合体（ＰＶＡ）を含有する。 <Dispersant for suspension polymerization>
The dispersant for suspension polymerization of the present invention (hereinafter sometimes referred to as "dispersant") contains a vinyl alcohol-based polymer (PVA).
（ＰＶＡ）
　前記ＰＶＡは、ビニルアルコール単位を構造単位として有する重合体である。前記ＰＶＡは下記式（１）で表される構造を有する。式（１）で表される構造は、通常、ＰＶＡの末端に位置する。 (PVA)
The PVA is a polymer having a vinyl alcohol unit as a structural unit. The PVA has a structure represented by the following formula (1). The structure represented by the formula (1) is usually located at the end of PVA.
Figure JPOXMLDOC01-appb-C000003
Figure JPOXMLDOC01-appb-C000003
　式（１）中、Ｒは炭素数４以上の炭化水素基である。Ｒの炭素数が４未満であると、分散剤の使用量が少ない場合に、平均粒子径が小さくかつ粗大粒子が少ない重合体粒子を得ることができない。また、前記ＰＶＡは、例えば炭素数５以上のアルデヒドを連鎖移動剤として用いて酢酸ビニルを重合した後、けん化することにより得ることができるが、炭素数３又は４のアルデヒドを用いた場合には、未反応のアルデヒドと酢酸ビニルとの分離が困難であり、酢酸ビニルを再利用することが困難となる。すなわち、式（１）中のＲが４以上である前記ＰＶＡは、生産効率に優れる。Ｒの炭素数の下限は、５が好ましく、６がより好ましい場合がある。一方、Ｒの炭素数の上限は、１２が好ましく、１０がより好ましく、８がさらに好ましい場合がある。Ｒの炭素数の上限が前記の値であると、平均粒子径が小さくかつ粗大粒子が少ない重合体粒子をより得やすく、また原料の入手性が優れるため安価に製造できる。 In formula (1), R is a hydrocarbon group having 4 or more carbon atoms. When the number of carbon atoms in R is less than 4, polymer particles having a small average particle size and a small number of coarse particles cannot be obtained when the amount of the dispersant used is small. Further, the PVA can be obtained by polymerizing vinyl acetate using, for example, an aldehyde having 5 or more carbon atoms as a chain transfer agent and then saponifying the vinyl acetate. However, when an aldehyde having 3 or 4 carbon atoms is used, the PVA can be obtained. , It is difficult to separate unreacted aldehyde and vinyl acetate, and it is difficult to reuse vinyl acetate. That is, the PVA in the formula (1) having an R of 4 or more is excellent in production efficiency. The lower limit of the carbon number of R is preferably 5 and may be more preferably 6. On the other hand, the upper limit of the number of carbon atoms of R is preferably 12, more preferably 10, and even more preferably 8. When the upper limit of the carbon number of R is the above value, it is easier to obtain polymer particles having a small average particle diameter and few coarse particles, and the availability of raw materials is excellent, so that the polymer particles can be produced at low cost.
　Ｒで表される炭化水素基は、フェニル基等の芳香族炭化水素基であってもよく、脂肪族炭化水素基であってもよいが、脂肪族炭化水素基であることが好ましい。脂肪族炭化水素基としては、アルキル基、アルケニル基、アルキニル基等の鎖状脂肪族炭化水素基、及びシクロアルキル基、シクロアルケニル基、シクロアルキニル基等の環状脂肪族炭化水素基を挙げることができるが、鎖状脂肪族炭化水素基が好ましい。鎖状脂肪族炭化水素基は、直鎖状の基であってもよく、分岐を有する基であってもよい。また、脂肪族炭化水素基は、アルキル基等の飽和脂肪族炭化水素基であってもよく、アルケニル基等の不飽和脂肪族炭化水素基であってもよいが、飽和脂肪族炭化水素基が好ましい。Ｒで表される炭化水素基としては、アルキル基がより好ましく、直鎖状アルキル基がさらに好ましい。Ｒで表されるアルキル基としては、ブチル基、ペンチル基、ヘキシル基、へプチル基、オクチル基、ノニル基、デシル基等が挙げられる。 The hydrocarbon group represented by R may be an aromatic hydrocarbon group such as a phenyl group or an aliphatic hydrocarbon group, but is preferably an aliphatic hydrocarbon group. Examples of the aliphatic hydrocarbon group include a chain aliphatic hydrocarbon group such as an alkyl group, an alkenyl group and an alkynyl group, and a cyclic aliphatic hydrocarbon group such as a cycloalkyl group, a cycloalkenyl group and a cycloalkynyl group. Although possible, chain aliphatic hydrocarbon groups are preferred. The chain aliphatic hydrocarbon group may be a linear group or a branched group. Further, the aliphatic hydrocarbon group may be a saturated aliphatic hydrocarbon group such as an alkyl group or an unsaturated aliphatic hydrocarbon group such as an alkenyl group, but the saturated aliphatic hydrocarbon group may be used. preferable. As the hydrocarbon group represented by R, an alkyl group is more preferable, and a linear alkyl group is further preferable. Examples of the alkyl group represented by R include a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group and the like.
　前記ＰＶＡは、下記式（２）を満たす。
　０．４≦［Ｘ］×１０２／［Ｒａ，１］２≦３．０　　　（２） The PVA satisfies the following formula (2).
0.4 ≤ [X] x 10 2 / [ Ra, 1 ] 2 ≤ 3.0 (2)
　式（２）中、［Ｘ］は前記ＰＶＡの全構造単位に対する式（１）で表される構造の含有率（モル％）である。［Ｒａ，１］は式（１）で表される構造と塩化ビニルとのＨＳＰ距離（（Ｊ／ｃｍ３）１／２）である。 In the formula (2), [X] is the content rate (mol%) of the structure represented by the formula (1) with respect to all the structural units of the PVA. [ Ra, 1 ] is the HSP distance ((J / cm 3 ) 1/2 ) between the structure represented by the formula (1) and vinyl chloride.
　本発明の分散剤は、式（２）を満たすＰＶＡを含有することにより、使用量が少ない場合であってもビニル系化合物の重合を安定させることができるため、重合が不安定なことに起因するブロック化が低減されるという優れた効果を発揮する。その結果、平均粒子径が小さくかつ粗大粒子が少なく、可塑剤吸収性も高い重合体粒子が得られる。 By containing PVA satisfying the formula (2), the dispersant of the present invention can stabilize the polymerization of the vinyl compound even when the amount used is small, which is caused by the unstable polymerization. It exerts an excellent effect of reducing blocking. As a result, polymer particles having a small average particle diameter, few coarse particles, and high plasticizer absorbability can be obtained.
　本発明の分散剤が前記効果を奏する理由は定かではないが、以下の理由が推測される。［Ｒａ，１］で表されるＨＳＰ距離が小さい場合、式（１）で表される構造と、塩化ビニル等のビニル系化合物との相溶性が高いことを意味する。また、式（１）で表される構造の含有量は、ＰＶＡとビニル系化合物との相溶性に影響を与える。このため、［Ｘ］×１０２／［Ｒａ，１］２は、ＰＶＡとビニル系化合物との相溶性の程度を表すことができると考えられる。［Ｘ］×１０２／［Ｒａ，１］２が０．４未満であると、懸濁重合の際、モノマーであるビニル系化合物と水との界面に存在するＰＶＡの量が少なくなり、平均粒子径が小さくかつ粗大粒子が少ない重合体粒子を得ることができない。一方、［Ｘ］×１０２／［Ｒａ，１］２が３．０を超えるＰＶＡは、製造が困難である。また、［Ｘ］×１０２／［Ｒａ，１］２が３．０を超えるＰＶＡは水溶性が低いため、懸濁重合を行う際のハンドリング性が悪い。［Ｘ］×１０２／［Ｒａ，１］２の下限は、０．５が好ましく、０．６がより好ましく、０．７がさらに好ましく、０．８、０．９又は０．９５が好ましい場合もある。一方、［Ｘ］×１０２／［Ｒａ，１］２の上限は、２．９が好ましく、２．８がより好ましく、２．７がさらに好ましく、２．６又は２．５が好ましい場合もある。 The reason why the dispersant of the present invention exerts the above effect is not clear, but the following reasons are presumed. When the HSP distance represented by [ Ra, 1 ] is small, it means that the structure represented by the formula (1) is highly compatible with a vinyl compound such as vinyl chloride. Further, the content of the structure represented by the formula (1) affects the compatibility between PVA and the vinyl compound. Therefore, it is considered that [X] × 10 2 / [ Ra, 1 ] 2 can represent the degree of compatibility between PVA and the vinyl compound. When [X] × 10 2 / [ Ra, 1 ] 2 is less than 0.4, the amount of PVA present at the interface between the vinyl-based compound as a monomer and water during suspension polymerization is reduced, and the amount of PVA is small. It is not possible to obtain polymer particles having a small average particle size and a small number of coarse particles. On the other hand, PVA in which [X] × 10 2 / [ Ra, 1 ] 2 exceeds 3.0 is difficult to produce. Further, PVA in which [X] × 10 2 / [ Ra, 1 ] 2 exceeds 3.0 has low water solubility, and therefore has poor handleability during suspension polymerization. The lower limit of [X] × 10 2 / [ Ra, 1 ] 2 is preferably 0.5, more preferably 0.6, still more preferably 0.7, and 0.8, 0.9 or 0.95. It may be preferable. On the other hand, the upper limit of [X] × 10 2 / [ Ra, 1 ] 2 is preferably 2.9, more preferably 2.8, further preferably 2.7, and preferably 2.6 or 2.5. There is also.
　前記ＰＶＡの全構造単位に対する式（１）で表される構造の含有率［Ｘ］の下限は、０．０１モル％が好ましく、０．０３モル％がより好ましく、０．０５モル％がさらに好ましく、０．０７モル％、０．０８モル％、０．０９モル％又は０．１０モル％がよりさらに好ましい場合がある。［Ｘ］が前記下限以上であることで、使用量が少ない場合にも、平均粒子径が小さくかつ粗大粒子が少ない重合体粒子をより得やすい。一方、前記［Ｘ］の上限は、３モル％が好ましく、２モル％がより好ましく、１．５モル％、１．２モル％、１．０モル％、０．８モル％、０．６モル％、０．５モル％又は０．４モル％がさらに好ましい場合がある。［Ｘ］が前記上限以下であることで、懸濁重合で得られる重合体粒子の可塑剤吸収性が優れる傾向にある。 The lower limit of the content rate [X] of the structure represented by the formula (1) with respect to all the structural units of PVA is preferably 0.01 mol%, more preferably 0.03 mol%, and further preferably 0.05 mol%. Preferably, 0.07 mol%, 0.08 mol%, 0.09 mol% or 0.10 mol% may be even more preferable. When [X] is at least the above lower limit, it is easier to obtain polymer particles having a small average particle diameter and a small number of coarse particles even when the amount used is small. On the other hand, the upper limit of the above [X] is preferably 3 mol%, more preferably 2 mol%, 1.5 mol%, 1.2 mol%, 1.0 mol%, 0.8 mol%, 0.6. More preferably, mol%, 0.5 mol% or 0.4 mol%. When [X] is not more than the above upper limit, the plasticizer absorbability of the polymer particles obtained by suspension polymerization tends to be excellent.
　前記［Ｘ］は、けん化度９９．５モル％まで再けん化したＰＶＡの１Ｈ－ＮＭＲ解析により算出できる。より詳細には、実施例に記載の方法により算出できる。 The above [X] can be calculated by 1 H-NMR analysis of PVA resaponified to a saponification degree of 99.5 mol%. More specifically, it can be calculated by the method described in Examples.
　式（１）で表される構造と塩化ビニルとのＨＳＰ距離［Ｒａ，１］の下限は、１（Ｊ／ｃｍ３）１／２が好ましく、２（Ｊ／ｃｍ３）１／２がより好ましく、２．５（Ｊ／ｃｍ３）１／２又は２．８（Ｊ／ｃｍ３）１／２がさらに好ましい場合がある。一方、式（１）で表される構造と塩化ビニルとのＨＳＰ距離［Ｒａ，１］の上限は、５．５（Ｊ／ｃｍ３）１／２が好ましく、４．９（Ｊ／ｃｍ３）１／２がより好ましく、４．５（Ｊ／ｃｍ３）１／２、４．２（Ｊ／ｃｍ３）１／２、４．０（Ｊ／ｃｍ３）１／２又は３．８（Ｊ／ｃｍ３）１／２が好ましい場合もある。［Ｒａ，１］が前記範囲内にあることで、使用量が少ない場合にも、平均粒子径が小さくかつ粗大粒子が少ない重合体粒子をより得やすく、係る重合体粒子の可塑剤吸収性も優れる傾向にある。 The lower limit of the HSP distance [ Ra, 1 ] between the structure represented by the formula (1) and vinyl chloride is preferably 1 (J / cm 3 ) 1/2 , and 2 (J / cm 3 ) 1/2 . More preferably, 2.5 (J / cm 3 ) 1/2 or 2.8 (J / cm 3 ) 1/2 may be even more preferred. On the other hand, the upper limit of the HSP distance [ Ra, 1 ] between the structure represented by the formula (1) and vinyl chloride is preferably 5.5 (J / cm 3 ) 1/2 , and 4.9 (J / cm). 3 ) 1/2 is more preferred, 4.5 (J / cm 3 ) 1/2 , 4.2 (J / cm 3 ) 1/2 , 4.0 (J / cm 3 ) 1/2 or 3. 8 (J / cm 3 ) 1/2 may be preferred. When [ Ra, 1 ] is within the above range, it is easier to obtain polymer particles having a small average particle diameter and a small number of coarse particles even when the amount used is small, and the plasticizer absorbability of the polymer particles. Also tends to be excellent.
　式（１）で表される構造と塩化ビニルとのＨＳＰ距離［Ｒａ，１］は、山本秀樹著「ＳＰ値：基礎・応用と計算方法」（２００５年発行、情報機構）及びＪ．Ｂｒａｎｄｒｕｐ著「ＰＯＬＹＭＥＲ　ＨＡＮＤＢＯＯＫ（ＦＯＵＲＴＨ　ＥＤＩＴＩＯＮ）」（２００３年発行、Ｗｉｌｅｙ）に記載の方法で算出できる。また、ＰＶＡ中の式（１）で表される構造の特定は、けん化度９９．５モル％まで再けん化したＰＶＡの１Ｈ－ＮＭＲ解析により算出でき、詳細には実施例に記載の方法により算出できる。 The HSP distance [ Ra, 1 ] between the structure represented by the formula (1) and vinyl chloride is described in Hideki Yamamoto, "SP Value: Basics, Applications and Calculation Methods" (published in 2005, Information Organization) and J. Mol. It can be calculated by the method described in "POLYMER HANDBOOK" (published in 2003, Wiley) by Brandrup. Further, the structure represented by the formula (1) in PVA can be calculated by 1 H-NMR analysis of PVA resaponified to a saponification degree of 99.5 mol%, and the details are described by the method described in Examples. Can be calculated.
　以下、ＨＳＰ距離［Ｒａ，１］の算出方法について詳述する。ある二つの物質の間のＨＳＰ距離は、ＨＳＰ値（δｄ、δｐ、δｈ）の値を三次元空間の座標と考えたときの二点間の距離に相当するパラメータである。ＨＳＰ値は分散項（δｄ）、極性項（δｐ）及び水素結合項（δｈ）の３成分で表される。例えば、式（１）で表される構造が下記式（４）で表される構造である場合、この構造のδｄ、δｐ及びδｈは、下記式（４）で表される構造のモル体積（Ｖ）を下記式（５）によって求めた上で、下記式（６）～（８）によって求めることができる。なお、下記式（５）中のｍは３以上の数であり、１Ｈ－ＮＭＲ解析における測定誤差、ＰＶＡに複数種の式（１）で表される構造が導入されている場合などのため、整数でなくてもよい。式（１）で表される構造が、下記式（４）で表される構造以外の構造である場合も、下記方法に準じ、山本秀樹著「ＳＰ値：基礎・応用と計算方法」（２００５年発行、情報機構）及びＪ．　Ｂｒａｎｄｒｕｐ著「ＰＯＬＹＭＥＲ　ＨＡＮＤＢＯＯＫ（ＦＯＵＲＴＨ　ＥＤＩＴＩＯＮ）」（２００３年発行、Ｗｉｌｅｙ）に記載の方法で算出できる。
　－（Ｃ＝Ｏ）－（ＣＨ２）ｍ－ＣＨ３　　　　　　（４）
　Ｖ＝３３．５＋１６．１ｍ＋１０．８　　（５）
　δｄ＝（４２０＋２７０ｍ＋２９０）／Ｖ　　（６）
　δｐ＝７７０／Ｖ　　（７）
　δｈ＝（２０００／Ｖ）１／２　　（８） Hereinafter, the calculation method of the HSP distance [ Ra, 1 ] will be described in detail. The HSP distance between two substances is a parameter corresponding to the distance between two points when the value of the HSP value (δd, δp, δh) is considered as the coordinates of the three-dimensional space. The HSP value is represented by three components, a dispersion term (δd), a polarity term (δp) and a hydrogen bond term (δh). For example, when the structure represented by the formula (1) is the structure represented by the following formula (4), δd, δp and δh of this structure are the molar volumes of the structure represented by the following formula (4). V) can be obtained by the following formula (5) and then by the following formulas (6) to (8). In addition, m in the following formula (5) is a number of 3 or more, because 1 measurement error in 1 H-NMR analysis, when a structure represented by a plurality of types of formula (1) is introduced in PVA, etc. , Does not have to be an integer. Even if the structure represented by the formula (1) is a structure other than the structure represented by the following formula (4), Hideki Yamamoto's "SP Value: Basics / Applications and Calculation Methods" (2005) is based on the following method. Published in the year, Information Organization) and J.M. It can be calculated by the method described in "POLYMER HANDBOOK" (published in 2003, Wiley) by Brandrup.
-(C = O)-(CH 2 ) m -CH 3 (4)
V = 33.5 + 16.1m + 10.8 (5)
δd = (420 + 270m + 290) / V (6)
δp = 770 / V (7)
δh = (2000 / V) 1/2 (8)
　また、塩化ビニルのＨＳＰ値は、（δＤ１、δＰ１、δＨ１）＝（１５．４、８．１、２．４）とする。 The HSP value of vinyl chloride is (δD 1 , δP 1 , δH 1 ) = (15.4, 8.1, 2.4).
　ＨＳＰ距離［Ｒａ，１］は、これらの値を用い、下記式（９）により求めることができる。
　［Ｒａ，１］＝｛４（δＤ１－δｄ）２＋（δＰ１－δｐ）２＋（δＨ１－δｈ）２｝１／２　　（９） The HSP distance [ Ra, 1 ] can be obtained by the following equation (9) using these values.
[R a, 1 ] = {4 (δD 1 -δd) 2 + (δP 1 -δp) 2 + (δH 1 -δh) 2 } 1/2 (9)
　前記ＰＶＡは、下記式（３）を満たすことが好ましい。
　３．５≦［Ｘ］×１０５／［Ｒａ，２］２≦２５　　（３） The PVA preferably satisfies the following formula (3).
3.5 ≤ [X] x 10 5 / [ Ra, 2 ] 2 ≤ 25 (3)
　式（３）中、［Ｘ］は前記ＰＶＡの全構造単位に対する式（１）で表される構造の含有率（モル％）である。［Ｒａ，２］は式（１）で表される構造と水とのＨＳＰ距離（（Ｊ／ｃｍ３）１／２）である。［Ｘ］×１０５／［Ｒａ，２］２の下限は、４が好ましく、６がより好ましく、７、８、９又は１０がさらに好ましい場合がある。一方、［Ｘ］×１０５／［Ｒａ，２］２の上限は、２２が好ましく、２０がより好ましく、１８、１６又は１５がさらに好ましい場合がある。［Ｘ］×１０５／［Ｒａ，２］２は、ＰＶＡと水との相溶性の程度を表すことができると考えられる。［Ｘ］×１０５／［Ｒａ，２］２が前記範囲内にあることで、使用量が少ない場合にも、平均粒子径が小さくかつ粗大粒子が少ない重合体粒子をより得やすく、係る重合体粒子の可塑剤吸収性も優れる傾向にある。 In the formula (3), [X] is the content rate (mol%) of the structure represented by the formula (1) with respect to all the structural units of the PVA. [ Ra, 2 ] is the HSP distance ((J / cm 3 ) 1/2 ) between the structure represented by the equation (1) and water. The lower limit of [X] × 10 5 / [ Ra, 2 ] 2 is preferably 4, more preferably 6, and even more preferably 7, 8, 9 or 10. On the other hand, the upper limit of [X] × 105 / [ Ra, 2 ] 2 is preferably 22 is preferable, 20 is more preferable, and 18, 16 or 15 may be further preferable. It is considered that [X] × 10 5 / [ Ra, 2 ] 2 can represent the degree of compatibility between PVA and water. Since [X] × 10 5 / [ Ra, 2 ] 2 is within the above range, it is easier to obtain polymer particles having a small average particle size and a small number of coarse particles even when the amount used is small. The plasticizer absorbability of the polymer particles also tends to be excellent.
　式（１）で表される構造と水とのＨＳＰ距離［Ｒａ，２］の上限は、４５（Ｊ／ｃｍ３）１／２が好ましく、４２（Ｊ／ｃｍ３）１／２がより好ましい場合もある。一方、式（１）で表される構造と水とのＨＳＰ距離［Ｒａ，２］の下限は、３６（Ｊ／ｃｍ３）１／２が好ましい。［Ｒａ，２］が前記範囲内にあることで、使用量が少ない場合にも、平均粒子径が小さくかつ粗大粒子が少ない重合体粒子をより得やすく、係る重合体粒子の可塑剤吸収性も優れる傾向にある。 The upper limit of the HSP distance [ Ra, 2 ] between the structure represented by the formula (1) and water is preferably 45 (J / cm 3 ) 1/2 , more preferably 42 (J / cm 3 ) 1/2 . It may be preferable. On the other hand, the lower limit of the HSP distance [ Ra, 2 ] between the structure represented by the formula (1) and water is preferably 36 (J / cm 3 ) 1/2 . When [ Ra, 2 ] is within the above range, it is easier to obtain polymer particles having a small average particle diameter and a small number of coarse particles even when the amount used is small, and the plasticizer absorbability of the polymer particles. Also tends to be excellent.
　式（１）で表される構造と水とのＨＳＰ距離［Ｒａ，２］は、山本秀樹著「ＳＰ値：基礎・応用と計算方法」（２００５年発行、情報機構）及びＪ．Ｂｒａｎｄｒｕｐ著「ＰＯＬＹＭＥＲ　ＨＡＮＤＢＯＯＫ（ＦＯＵＲＴＨ　ＥＤＩＴＩＯＮ）」（２００３年発行、Ｗｉｌｅｙ）に記載の方法で算出できる。具体的には、前記したＨＳＰ距離［Ｒａ，１］と同様の方法にて算出できる。すなわち、ＨＳＰ距離［Ｒａ，２］は、式（１）で表される構造のＨＳＰ値（δｄ、δｐ、δｈ）と、水のＨＳＰ値（δＤ２、δＰ２、δＨ２）とから、下記式（１０）により求めることができる。なお、水のＨＳＰ値は、（δＤ２、δＰ２、δＨ２）＝（１５．５、１６．０、４２．４）とする。
　［Ｒａ，２］＝｛４（δＤ２－δｄ）２＋（δＰ２－δｐ）２＋（δＨ２－δｈ）２｝１／２　　（１０） The HSP distance [ Ra, 2 ] between the structure represented by the equation (1) and water is described in Hideki Yamamoto, "SP Value: Basics, Applications and Calculation Methods" (published in 2005, Information Organization) and J. Mol. It can be calculated by the method described in "POLYMER HANDBOOK" (published in 2003, Wiley) by Brandrup. Specifically, it can be calculated by the same method as the above-mentioned HSP distance [ Ra, 1 ]. That is, the HSP distance [ Ra, 2 ] is determined from the HSP values (δd, δp, δh) of the structure represented by the equation (1) and the HSP values (δD 2 , δP 2 , δH 2 ) of water. It can be obtained by the following formula (10). The HSP value of water is (δD 2 , δP 2 , δH 2 ) = (15.5, 16.0, 42.4).
[R a, 2 ] = {4 (δD 2 -δd) 2 + (δP 2 -δp) 2 + (δH 2 -δh) 2 } 1/2 (10)
　通常、前記ＰＶＡは、後に詳述するように、炭素数５以上のアルデヒドの存在下でビニルエステルを重合し、得られたビニルエステル系重合体をけん化することで得られる。前記ＰＶＡのけん化度の下限としては、２０モル％が好ましく、３０モル％がより好ましく、４０モル％がさらに好ましい場合がある。一方、前記けん化度の上限は、１００モル％であってよいが、９９．５モル％が好ましく、９９．２モル％がより好ましく、９９モル％がさらに好ましく、９５モル％又は９０モル％が好ましい場合がある。本発明の分散剤を一次分散剤として使用する場合には、前記ＰＶＡのけん化度の下限は６０モル％が好ましく、６５モル％がより好ましく、６８モル％がさらに好ましい。本発明の分散剤を二次分散剤として使用する場合には、前記ＰＶＡのけん化度の上限は８０モル％が好ましく、７０モル％がより好ましく、６０モル％がさらに好ましい場合がある。前記ＰＶＡのけん化度が前記範囲であることで、界面活性性能が好適化されることなどにより、本発明の効果がより向上する。なお、一次分散剤とは、懸濁重合の際にモノマーの分散性を高め、得られる重合体粒子の粒径を制御するなどのために用いられる添加剤である。一方、二次分散剤とは、通常、特に得られる重合体粒子の空孔率を高めることなどのために、一次分散剤と共に用いられる添加剤である。けん化度は、ＪＩＳ　Ｋ　６７２６：１９９４に記載の方法により測定される値である。 Usually, the PVA is obtained by polymerizing a vinyl ester in the presence of an aldehyde having 5 or more carbon atoms and saponifying the obtained vinyl ester-based polymer, as will be described in detail later. As the lower limit of the saponification degree of PVA, 20 mol% is preferable, 30 mol% is more preferable, and 40 mol% may be further preferable. On the other hand, the upper limit of the degree of saponification may be 100 mol%, but 99.5 mol% is preferable, 99.2 mol% is more preferable, 99 mol% is further preferable, and 95 mol% or 90 mol% is preferable. It may be preferable. When the dispersant of the present invention is used as the primary dispersant, the lower limit of the saponification degree of the PVA is preferably 60 mol%, more preferably 65 mol%, still more preferably 68 mol%. When the dispersant of the present invention is used as a secondary dispersant, the upper limit of the saponification degree of the PVA is preferably 80 mol%, more preferably 70 mol%, and even more preferably 60 mol%. When the degree of saponification of PVA is within the above range, the surface activity performance is optimized, and the effect of the present invention is further improved. The primary dispersant is an additive used for enhancing the dispersibility of the monomer during suspension polymerization and controlling the particle size of the obtained polymer particles. On the other hand, the secondary dispersant is an additive usually used together with the primary dispersant in order to increase the porosity of the obtained polymer particles. The saponification degree is a value measured by the method described in JIS K 6726: 1994.
　前記ＰＶＡの粘度平均重合度の下限としては、１００が好ましく、１２０がより好ましく、１５０がさらに好ましく、１６０がよりさらに好ましく、２００、３００、４００、５００又は６００がよりさらに好ましい場合がある。粘度平均重合度が前記下限以上であることで、保護コロイド性が高まり、重合安定性等の分散剤としての諸性能がより高まる。一方、この粘度平均重合度の上限としては、５，０００が好ましく、３，５００がより好ましく、２，０００がさらに好ましく、１，５００、１，０００又は８００がよりさらに好ましい場合がある。粘度平均重合度が前記上限以下であることで、界面活性性能が高まり、分散剤としての諸性能がより向上する。本発明の分散剤を一次分散剤として使用する場合には、前記ＰＶＡの粘度平均重合度の下限は２００が好ましく、３００がより好ましく、４００がさらに好ましく、５００がよりさらに好ましく、６００が特に好ましい。当該分散剤を二次分散剤として使用する場合には、前記ＰＶＡの粘度平均重合度の上限は、８００が好ましく、７００がより好ましく、６００がさらに好ましい。ＰＶＡの粘度平均重合度は、ＪＩＳ　Ｋ　６７２６：１９９４に準じて測定した値である。すなわち、ＰＶＡをけん化度９９．５モル％以上に再けん化し、生成した後、３０℃の水中で測定した極限粘度［η］（リットル／ｇ）から下記式（１１）により求めることができる。
　粘度平均重合度＝（［η］×１０４／８．２９）（１／０．６２）　（１１） As the lower limit of the viscosity average degree of polymerization of PVA, 100 is preferable, 120 is more preferable, 150 is further preferable, 160 is further preferable, and 200, 300, 400, 500 or 600 may be further preferable. When the viscosity average degree of polymerization is at least the above lower limit, the protective colloidal property is enhanced, and various performances as a dispersant such as polymerization stability are further enhanced. On the other hand, the upper limit of the viscosity average degree of polymerization is preferably 5,000, more preferably 3,500, still more preferably 2,000, and even more preferably 1,500, 1,000 or 800. When the viscosity average degree of polymerization is not more than the above upper limit, the surface active performance is enhanced and various performances as a dispersant are further improved. When the dispersant of the present invention is used as the primary dispersant, the lower limit of the viscosity average degree of polymerization of PVA is preferably 200, more preferably 300, still more preferably 400, still more preferably 500, and particularly preferably 600. .. When the dispersant is used as a secondary dispersant, the upper limit of the viscosity average degree of polymerization of PVA is preferably 800, more preferably 700, and even more preferably 600. The viscosity average degree of polymerization of PVA is a value measured according to JIS K 6726: 1994. That is, PVA can be re-saponified to a saponification degree of 99.5 mol% or more, produced, and then obtained from the ultimate viscosity [η] (liter / g) measured in water at 30 ° C. by the following formula (11).
Viscosity average degree of polymerization = ([η] × 10 4 / 8.29) (1 / 0.62) (11)
　前記ＰＶＡは、下記式（１２）で表される構造を有することが好ましい。
　－ＣＯ－（ＣＨ＝ＣＨ）ｐ－　　　（１２）
　式（１２）中、ｐは、１～５の整数である。 The PVA preferably has a structure represented by the following formula (12).
-CO- (CH = CH) p- (12)
In equation (12), p is an integer of 1 to 5.
　前記式（１２）で表される構造は、例えば、式（１）で表される構造を有するＰＶＡを熱処理することにより形成される。前記式（１２）で表される構造中のカルボニル基と、前記式（１）で表される構造中のカルボニル基とは、同一のものであってよい。すなわち、前記ＰＶＡの末端構造は、Ｒ－ＣＯ－（ＣＨ＝ＣＨ）ｐ－で表される構造であってよい。前記ＰＶＡが前記式（１２）で表される構造を有する場合、波長３２０ｎｍの吸光が生じる。そのため、前記ＰＶＡの０．１質量％水溶液の光路長１０ｍｍ、波長３２０ｎｍにおける吸光度の下限は、０．０５が好ましく、０．１がより好ましく、０．１５、０．２０又は０．２５がさらに好ましい場合がある。前記吸光度が前記下限以上である場合、前記式（１２）で表される構造が十分にＰＶＡに形成されており、より平均粒子径が小さく且つ粗大粒子が少ない重合体粒子を得ることができる。従って、このような場合、特に使用量が少ない場合にも、平均粒子径が小さくかつ粗大粒子が少なく、可塑剤吸収性が良好な重合体粒子を得ることができる。 The structure represented by the formula (12) is formed, for example, by heat-treating a PVA having the structure represented by the formula (1). The carbonyl group in the structure represented by the formula (12) and the carbonyl group in the structure represented by the formula (1) may be the same. That is, the terminal structure of the PVA may be a structure represented by R-CO- (CH = CH) p- . When the PVA has the structure represented by the formula (12), absorption having a wavelength of 320 nm occurs. Therefore, the lower limit of the absorbance of the 0.1 mass% aqueous solution of PVA at an optical path length of 10 mm and a wavelength of 320 nm is preferably 0.05, more preferably 0.1, and further preferably 0.15, 0.25 or 0.25. It may be preferable. When the absorbance is at least the lower limit, the structure represented by the formula (12) is sufficiently formed in PVA, and polymer particles having a smaller average particle diameter and fewer coarse particles can be obtained. Therefore, in such a case, even when the amount used is particularly small, polymer particles having a small average particle diameter, a small number of coarse particles, and good plasticizer absorbability can be obtained.
　一方、前記ＰＶＡの０．１質量％水溶液の光路長１０ｍｍ、波長３２０ｎｍにおける吸光度の上限は、０．４が好ましく、０．３５がより好ましく、０．３０又は０．２５がさらに好ましい場合がある。前記ＰＶＡにおいて、前記式（１２）で表される構造が過剰に形成されている場合、得られる重合体粒子の可塑剤吸収性に影響を与えることがある。従って、前記吸光度が前記上限以下である場合、得られる重合体粒子の可塑剤吸収性を高めることができる。 On the other hand, the upper limit of the absorbance of the 0.1 mass% aqueous solution of PVA at an optical path length of 10 mm and a wavelength of 320 nm is preferably 0.4, more preferably 0.35, and even more preferably 0.30 or 0.25. .. If the structure represented by the formula (12) is excessively formed in the PVA, it may affect the plasticizer absorbability of the obtained polymer particles. Therefore, when the absorbance is not more than the upper limit, the plasticizer absorbability of the obtained polymer particles can be enhanced.
　前記ＰＶＡが末端にホルミル基（－ＣＯＨ）を有する場合、その含有率は前記ＰＶＡの全構造単位に対して、３．５ミリモル％以下が好ましく、３．０ミリモル％以下がより好ましく、２．５ミリモル％以下がさらに好ましい場合がある。前記含有率の下限に特に制限はなく、実質的に末端にホルミル基を有していなくてもよい。本発明においては、ＰＶＡの末端に存在するホルミル基が少ないことで、分散剤としての諸性能が高まる場合があり、特に得られる重合体粒子の可塑剤吸収性が向上する場合がある。なお、ＰＶＡの末端のホルミル基の含有率は、酸素が供給される系で重合を行った場合などに高まる傾向にある。また、ＰＶＡの重合度も末端のホルミル基の含有率に影響する。前記ホルミル基の含有率は、前記ＰＶＡをメタノール等により洗浄し、未反応のアルデヒド等を除去した状態で、１Ｈ－ＮＭＲ測定を行うことにより算出できる。 When the PVA has a formyl group (-COH) at the terminal, the content thereof is preferably 3.5 mmol% or less, more preferably 3.0 mmol% or less, based on the total structural units of the PVA. 5 mmol% or less may be more preferred. The lower limit of the content is not particularly limited, and it does not have to have a formyl group at the terminal substantially. In the present invention, since the number of formyl groups present at the terminal of PVA is small, various performances as a dispersant may be improved, and in particular, the plasticizer absorbability of the obtained polymer particles may be improved. The content of the formyl group at the terminal of PVA tends to increase when the polymerization is carried out in a system to which oxygen is supplied. The degree of polymerization of PVA also affects the content of formyl groups at the ends. The content of the formyl group can be calculated by performing 1 H-NMR measurement in a state where the PVA is washed with methanol or the like and unreacted aldehyde or the like is removed.
　前記ＰＶＡは、前記式（１）で表される構造、及びビニルエステルに由来する構造単位（ビニルアルコール単位及びビニルエステル単位）以外の他の構造単位を有していてもよい。前記他の構造単位を与える単量体としては、例えばエチレン、プロピレン、ｎ－ブテン、イソブチレン等のα－オレフィン；アクリル酸及びその塩；アクリル酸メチル、アクリル酸エチル、アクリル酸ｎ－プロピル、アクリル酸ｉ－プロピル、アクリル酸ｎ－ブチル、アクリル酸ｉ－ブチル、アクリル酸ｔ－ブチル、アクリル酸２－エチルヘキシル、アクリル酸ドデシル、アクリル酸オクタデシル等のアクリル酸エステル；メタクリル酸及びその塩；メタクリル酸メチル、メタクリル酸エチル、メタクリル酸ｎ－プロピル、メタクリル酸ｉ－プロピル、メタクリル酸ｎ－ブチル、メタクリル酸ｉ－ブチル、メタクリル酸ｔ－ブチル、メタクリル酸２－エチルヘキシル、メタクリル酸ドデシル、メタクリル酸オクタデシル等のメタクリル酸エステル；アクリルアミド；Ｎ－メチルアクリルアミド、Ｎ－エチルアクリルアミド、Ｎ，Ｎ－ジメチルアクリルアミド、ジアセトンアクリルアミド、アクリルアミドプロパンスルホン酸及びその塩、アクリルアミドプロピルジメチルアミン及びその塩又はその４級塩、Ｎ－メチロールアクリルアミド及びその誘導体等のアクリルアミド誘導体；メタクリルアミド；Ｎ－メチルメタクリルアミド、Ｎ－エチルメタクリルアミド、メタクリルアミドプロパンスルホン酸及びその塩、メタクリルアミドプロピルジメチルアミン及びその塩又はその４級塩、Ｎ－メチロールメタクリルアミド及びその誘導体等のメタクリルアミド誘導体；メチルビニルエーテル、エチルビニルエーテル、ｎ－プロピルビニルエーテル、ｉ－プロピルビニルエーテル、ｎ－ブチルビニルエーテル、ｉ－ブチルビニルエーテル、ｔ－ブチルビニルエーテル、ドデシルビニルエーテル、ステアリルビニルエーテル等のビニルエーテル；アクリロニトリル、メタクリロニトリル等のニトリル；塩化ビニル、フッ化ビニル等のハロゲン化ビニル；塩化ビニリデン、フッ化ビニリデン等のハロゲン化ビニリデン；酢酸アリル、塩化アリル等のアリル化合物；マレイン酸、イタコン酸、フマル酸等の不飽和ジカルボン酸及びその塩又はそのモノ又はジアルキルエステル；ビニルトリメトキシシラン等のビニルシリル化合物；酢酸イソプロペニル、３，４－ジアセトキシ－１－ブテン等が挙げられる。他の単量体は、１種又は２種以上を用いることができる。 The PVA may have a structure represented by the formula (1) and a structural unit other than the structural unit (vinyl alcohol unit and vinyl ester unit) derived from vinyl ester. Examples of the monomer giving the other structural unit include α-olefins such as ethylene, propylene, n-butene, and isobutylene; acrylic acid and salts thereof; methyl acrylate, ethyl acrylate, n-propyl acrylate, and acrylic. Acrylic acid esters such as i-propyl acid, n-butyl acrylate, i-butyl acrylate, t-butyl acrylate, 2-ethylhexyl acrylate, dodecyl acrylate, octadecyl acrylate; methacrylic acid and salts thereof; methacrylic acid Methyl, ethyl methacrylate, n-propyl methacrylate, i-propyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, t-butyl methacrylate, 2-ethylhexyl methacrylate, dodecyl methacrylate, octadecyl methacrylate, etc. Acrylic acid ester; acrylamide; N-methylacrylamide, N-ethylacrylamide, N, N-dimethylacrylamide, diacetoneacrylamide, acrylamide propanesulfonic acid and its salts, acrylamidepropyldimethylamine and its salts or quaternary salts thereof, N -Acrylamide derivatives such as methylolacrylamide and its derivatives; methacrylicamide; N-methylmethacrylicamide, N-ethylmethacrylicamide, methacrylicamide propanesulfonic acid and its salts, methacrylicamidepropyldimethylamine and its salts or quaternary salts thereof, N -Methylamide derivatives such as methylolmethacrylicamide and its derivatives; methylvinyl ether, ethylvinyl ether, n-propylvinyl ether, i-propylvinyl ether, n-butylvinyl ether, i-butylvinyl ether, t-butylvinyl ether, dodecylvinyl ether, stearylvinyl ether and the like. Vinyl ether; nitriles such as acrylic nitrile and methacrylonitrile; vinyl halides such as vinyl chloride and vinyl fluoride; vinylidene halides such as vinylidene chloride and vinylidene fluoride; allyl compounds such as allyl acetate and allyl chloride; maleic acid and itacone. Examples thereof include unsaturated dicarboxylic acids such as acids and fumaric acids and salts thereof or mono or dialkyl esters thereof; vinylsilyl compounds such as vinyltrimethoxysilane; isopropenyl acetate, 3,4-diacetoxy-1-butene and the like. As the other monomer, one kind or two or more kinds can be used.
　前記ＰＶＡにおける全構造単位に対する前記他の構造単位の割合は、２０モル％以下が好ましいことがあり、１０モル％以下がより好ましいことがあり、５モル％、３モル％又は１モル％がさらに好ましい場合がある。一方、前記他の構造単位の割合は、例えば０．１モル％以上であってよく、１モル％以上であってもよい。 The ratio of the other structural units to the total structural units in the PVA may be preferably 20 mol% or less, more preferably 10 mol% or less, and further preferably 5 mol%, 3 mol% or 1 mol%. It may be preferable. On the other hand, the ratio of the other structural units may be, for example, 0.1 mol% or more, and may be 1 mol% or more.
（ＰＶＡの製造方法）
　本発明の分散剤に含まれるＰＶＡの製造方法は特に限定されないが、例えば、変性剤として炭素数５以上のアルデヒドを添加してビニルエステル単量体を重合し、得られたビニルエステル系重合体をけん化する方法が挙げられる。 (Manufacturing method of PVA)
The method for producing PVA contained in the dispersant of the present invention is not particularly limited, but for example, a vinyl ester-based polymer obtained by polymerizing a vinyl ester monomer by adding an aldehyde having 5 or more carbon atoms as a modifier is added. There is a method to polymerize.
　前記アルデヒドとしては、アルキルアルデヒドが好ましく、例えば、１－ペンタナール、１－ヘキサナール、１－へプタナール、１－オクタナール、１－ノナナール、１－デカナール、１－ウンデカナール等の直鎖アルキルアルデヒド；７－オクテナール等の直鎖アルケニルアルデヒド；２－メチルブタナール、２－エチルヘキサナール、２－エチルブタナール、２－メチルウンデカナール等の分岐アルキルアルデヒドが挙げられる。前記アルデヒドは１種を単独で使用してよく、２種以上を併用してもよい。前記アルデヒドの存在下でビニルエステル単量体を重合することで、前記アルデヒドが連鎖移動剤として作用し、式（１）で表される構造を有するＰＶＡを容易に製造できる。前記アルデヒドの使用量は特に制限されないが、例えば、ビニルエステル単量体１００質量部に対して０．５質量部以上２０質量部以下が好ましい。 As the aldehyde, an alkyl aldehyde is preferable, and for example, a linear alkyl aldehyde such as 1-pentanal, 1-hexanal, 1-heptanal, 1-octanal, 1-nonanal, 1-decanal, 1-undecanal; 7- Linear alkenyl aldehydes such as octanal; branched alkyl aldehydes such as 2-methylbutanal, 2-ethylhexanal, 2-ethylbutanal and 2-methylundecanal can be mentioned. The aldehyde may be used alone or in combination of two or more. By polymerizing the vinyl ester monomer in the presence of the aldehyde, the aldehyde acts as a chain transfer agent, and PVA having the structure represented by the formula (1) can be easily produced. The amount of the aldehyde used is not particularly limited, but is preferably 0.5 parts by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the vinyl ester monomer.
　前記アルデヒドは、通常、連鎖移動剤として働く。ビニルエステル単量体を重合する際は、前記アルデヒド以外の他の連鎖移動剤を併用してもよい。他の連鎖移動剤としては、例えば前記アルデヒド以外のアルデヒド（例えば、アセトアルデヒド、１－プロパナール、１－ブタナール）；アセトン、メチルエチルケトン、ヘキサノン、シクロヘキサノン等のケトン；２－ヒドロキシエタンチオール等のメルカプタン；３－メルカプトプロピオン酸、チオ酢酸等のチオカルボン酸；トリクロロエチレン、パークロロエチレン等のハロゲン化炭化水素などが挙げられる。連鎖移動剤の添加量は、この連鎖移動剤の連鎖移動定数、達成すべきＰＶＡの重合度等に応じて決定すればよい。 The aldehyde usually acts as a chain transfer agent. When polymerizing the vinyl ester monomer, a chain transfer agent other than the aldehyde may be used in combination. Other chain transfer agents include, for example, aldehydes other than the above aldehydes (eg, acetaldehyde, 1-propanol, 1-butanal); ketones such as acetone, methyl ethyl ketone, hexanone, cyclohexanone; mercaptans such as 2-hydroxyethanethiol; 3 -Thiocarboxylic acids such as mercaptopropionic acid and thioacetic acid; halogenated hydrocarbons such as trichlorethylene and perchloroethylene can be mentioned. The amount of the chain transfer agent added may be determined according to the chain transfer constant of the chain transfer agent, the degree of polymerization of PVA to be achieved, and the like.
　ビニルエステル単量体の重合方法としては、例えば塊状重合法、溶液重合法、懸濁重合法、乳化重合法、分散重合法等が挙げられ、工業的観点から、溶液重合法、乳化重合法又は分散重合法が好ましい。ビニルエステル単量体の重合は、回分法、半回分法及び連続法のいずれの重合方式であってもよい。 Examples of the method for polymerizing the vinyl ester monomer include a bulk polymerization method, a solution polymerization method, a suspension polymerization method, an emulsion polymerization method, a dispersion polymerization method, and the like, and from an industrial point of view, a solution polymerization method, an emulsion polymerization method, or the like. The dispersion polymerization method is preferable. The polymerization of the vinyl ester monomer may be carried out by any of a batch method, a semi-batch method and a continuous method.
　ビニルエステル単量体としては、例えば酢酸ビニル、ギ酸ビニル、プロピオン酸ビニル、カプリル酸ビニル、バーサチック酸ビニル等が挙げられ、これらの中でも、工業的観点から酢酸ビニルが好ましい。前記ＰＶＡは、１種類のビニルエステル単量体の単独重合体であってもよく、異なるビニルエステル単量体の共重合体であってもよい。 Examples of the vinyl ester monomer include vinyl acetate, vinyl formate, vinyl propionate, vinyl caprylate, vinyl versatic acid and the like, and among these, vinyl acetate is preferable from an industrial point of view. The PVA may be a homopolymer of one kind of vinyl ester monomer or a copolymer of different vinyl ester monomers.
　重合に使用される重合開始剤は、公知の重合開始剤、例えばアゾ系開始剤、過酸化物系開始剤、レドックス系開始剤から重合方法に応じて選択される。アゾ系開始剤は、例えば、２，２’－アゾビスイソブチロニトリル、２，２’－アゾビス（２，４－ジメチルバレロニトリル）、２，２’－アゾビス（４－メトキシ－２，４－ジメチルバレロニトリル）等が挙げられる。過酸化物系開始剤は、例えば、ジイソプロピルペルオキシジカーボネート、ジ（２－エチルヘキシル）ペルオキシジカーボネート、ジエトキシエチルペルオキシジカーボネート等のペルオキシジカーボネート系化合物；ｔ－ブチルペルオキシネオデカネート、α－クミルペルオキシネオデカネート等のパーエステル化合物；アセチルシクロヘキシルスルホニルペルオキシド；２，４，４－トリメチルペンチル－２－ペルオキシフェノキシアセテート等が挙げられる。過硫酸カリウム、過硫酸アンモニウム、過酸化水素等を前記開始剤に組み合わせて重合開始剤としてもよい。レドックス系開始剤は、例えば前記の過酸化物系開始剤或いは酸化剤（過硫酸カリウム、過硫酸アンモニウム、過酸化水素水等）と、亜硫酸水素ナトリウム、炭酸水素ナトリウム、酒石酸、Ｌ－アスコルビン酸、ロンガリット等の還元剤とを組み合わせた重合開始剤である。重合開始剤の使用量は、重合触媒により異なるために一概には決められないが、重合速度に応じて選択される。 The polymerization initiator used for the polymerization is selected from known polymerization initiators such as azo-based initiators, peroxide-based initiators, and redox-based initiators according to the polymerization method. The azo-based initiator is, for example, 2,2'-azobisisobutyronitrile, 2,2'-azobis (2,4-dimethylvaleronitrile), 2,2'-azobis (4-methoxy-2,4). -Dimethylvaleronitrile) and the like. The peroxide peroxide-based initiator is a peroxydicarbonate-based compound such as diisopropylperoxydicarbonate, di (2-ethylhexyl) peroxydicarbonate, diethoxyethylperoxydicarbonate; t-butylperoxyneodecanate, α-c. Perester compounds such as milperoxyneodecanate; acetylcyclohexylsulfonyl peroxides; 2,4,4-trimethylpentyl-2-peroxyphenoxyacetate and the like. Potassium persulfate, ammonium persulfate, hydrogen peroxide and the like may be combined with the initiator to obtain a polymerization initiator. The redox-based initiator is, for example, the above-mentioned peroxide-based initiator or oxidizing agent (potassium persulfate, ammonium persulfate, hydrogen peroxide solution, etc.), sodium bisulfite, sodium hydrogencarbonate, tartrate acid, L-ascorbic acid, longalit. It is a polymerization initiator in combination with a reducing agent such as. The amount of the polymerization initiator used varies depending on the polymerization catalyst and cannot be unconditionally determined, but is selected according to the polymerization rate.
　前記ＰＶＡは、本発明の趣旨を損なわない範囲で、ビニルエステル単量体と共重合可能な他の不飽和単量体とを共重合させたビニルエステル共重合体をけん化したものであってもよい。他の単量体は、前記した他の構造単位を与える単量体が例示される。 The PVA may be a saponified vinyl ester copolymer obtained by copolymerizing a vinyl ester monomer with another copolymerizable unsaturated monomer to the extent that the gist of the present invention is not impaired. good. Examples of the other monomer include the monomers giving the other structural units described above.
　前記ＰＶＡは、水溶性を向上させる目的で、ビニルエステル単量体と共に、不飽和カルボン酸類、不飽和ジカルボン酸類、これらの塩、又はこれらのモノ若しくはジアルキルエステル等の不飽和単量体を共重合させたビニルエステル系共重合体をけん化して製造してもよい。連鎖移動剤としてアルキルチオールを使用して製造したＰＶＡは水溶性が低く、前記不飽和カルボン酸類等を共重合させたり、水溶液を調整する際にメタノール等の有機溶剤を使用したりといった措置が必要となることが多い。一方で、式（１）で表される構造を有し、式（２）を満たすＰＶＡは、アルキルチオールと同じ炭素数の炭化水素鎖を有する場合であっても比較的水溶性が高い。そのため、必ずしも前記の措置をとる必要がなく、係る点からも本発明は優れている。 The PVA copolymerizes unsaturated carboxylic acids, unsaturated dicarboxylic acids, salts thereof, or unsaturated monomers such as mono or dialkyl esters thereof together with vinyl ester monomers for the purpose of improving water solubility. The vinyl ester-based copolymer that has been subjected to the above may be saponified to produce the copolymer. PVA produced using alkylthiol as a chain transfer agent has low water solubility, and it is necessary to take measures such as copolymerizing the unsaturated carboxylic acids and the like, and using an organic solvent such as methanol when preparing an aqueous solution. Often becomes. On the other hand, PVA having the structure represented by the formula (1) and satisfying the formula (2) is relatively highly water-soluble even when it has a hydrocarbon chain having the same carbon number as the alkyl thiol. Therefore, it is not always necessary to take the above-mentioned measures, and the present invention is excellent in this respect as well.
　ビニルエステル重合体のけん化反応には、公知の水酸化ナトリウム、水酸化カリウム、ナトリウムメトキシド等の塩基性触媒、又はｐ－トルエンスルホン酸等の酸性触媒を用いた加アルコール分解ないし加水分解反応を適用できる。 For the saponification reaction of the vinyl ester polymer, an alcoholic decomposition or hydrolysis reaction using a known basic catalyst such as sodium hydroxide, potassium hydroxide or sodium methoxyd or an acidic catalyst such as p-toluenesulfonic acid is carried out. Applicable.
　けん化反応に用いられる溶媒としては、メタノール、エタノール等のアルコール；酢酸メチル、酢酸エチル等のエステル；アセトン、メチルエチルケトン等のケトン；ベンゼン、トルエン等の芳香族炭化水素などが挙げられ、これらは１種を単独で使用しても、２種以上を併用してもよい。中でも、メタノール又はメタノールと酢酸メチルとの混合溶液を溶媒として用い、塩基性触媒である水酸化ナトリウムの存在下にけん化反応を行うのが簡便であり好ましい。 Examples of the solvent used for the saponification reaction include alcohols such as methanol and ethanol; esters such as methyl acetate and ethyl acetate; ketones such as acetone and methyl ethyl ketone; aromatic hydrocarbons such as benzene and toluene, and these are one type. May be used alone or in combination of two or more. Above all, it is convenient and preferable to carry out the saponification reaction in the presence of sodium hydroxide as a basic catalyst using methanol or a mixed solution of methanol and methyl acetate as a solvent.
　また、けん化工程以降の工程として、ＰＶＡを含む樹脂固形物を洗浄する工程、ＰＶＡを含む樹脂固形物を乾燥する工程、ＰＶＡを含む樹脂固形物を熱処理する工程等をさらに備えていてもよい。熱処理を行う場合の処理温度としては、例えば１００℃以上１５０℃以下とすることができる。また、処理時間としては、例えば１０分以上３時間以下とすることができる。 Further, as the steps after the saponification step, a step of cleaning the resin solid matter containing PVA, a step of drying the resin solid matter containing PVA, a step of heat-treating the resin solid matter containing PVA, and the like may be further provided. The treatment temperature for heat treatment can be, for example, 100 ° C. or higher and 150 ° C. or lower. The processing time can be, for example, 10 minutes or more and 3 hours or less.
（他の成分、用途等）
　本発明の分散剤は、前記ＰＶＡを含み、さらに他の成分を含んでいてもよい。本発明の分散剤の不揮発分中の前記ＰＶＡの含有量の下限としては、３０質量％が好ましく、５０質量％がより好ましく、７０質量％、９０質量％又は９９質量％がさらに好ましい場合もある。本発明の分散剤の不揮発分中の前記ＰＶＡの含有量の上限は１００質量％であってよい。本発明の分散剤に含まれていてよい前記ＰＶＡ以外の不揮発分は、前記ＰＶＡ以外のＰＶＡ、ＰＶＡ以外の樹脂、界面活性剤、可塑剤等の添加剤、製造時に用いられた各化合物等が挙げられる。本発明の分散剤の不揮発分中の全てのＰＶＡの含有量の下限としては、５０質量％が好ましく、７０質量％がより好ましく、８０質量％、９０質量％又は９９質量％がさらに好ましい場合もある。本発明の分散剤の不揮発分中の全てのＰＶＡの含有量の上限は１００質量％であってよい。また、本発明の分散剤における揮発分の含有量は、通常２０質量％以下であり、１５質量％以下が好ましく、１０質量％以下がより好ましい。本発明の分散剤に含まれ得る揮発分としては、アルコール、水等が挙げられる。すなわち、本発明の分散剤は、実質的に本発明のＰＶＡからなるものであってよい。本発明の分散剤の形状は特に限定されないが、通常、粉体である。 (Other ingredients, uses, etc.)
The dispersant of the present invention contains the PVA and may further contain other components. The lower limit of the content of the PVA in the non-volatile content of the dispersant of the present invention is preferably 30% by mass, more preferably 50% by mass, and even more preferably 70% by mass, 90% by mass or 99% by mass. .. The upper limit of the content of the PVA in the non-volatile content of the dispersant of the present invention may be 100% by mass. The non-volatile components other than PVA that may be contained in the dispersant of the present invention include PVA other than PVA, resins other than PVA, surfactants, additives such as plasticizers, and compounds used at the time of production. Can be mentioned. The lower limit of the content of all PVA in the non-volatile content of the dispersant of the present invention is preferably 50% by mass, more preferably 70% by mass, and even more preferably 80% by mass, 90% by mass or 99% by mass. be. The upper limit of the content of all PVA in the non-volatile content of the dispersant of the present invention may be 100% by mass. The content of the volatile content in the dispersant of the present invention is usually 20% by mass or less, preferably 15% by mass or less, and more preferably 10% by mass or less. Examples of the volatile matter that can be contained in the dispersant of the present invention include alcohol, water and the like. That is, the dispersant of the present invention may be substantially composed of the PVA of the present invention. The shape of the dispersant of the present invention is not particularly limited, but it is usually a powder.
　本発明の分散剤は、一次分散剤（主分散剤又は分散安定剤ともいう）及び二次分散剤（分散助剤ともいう）のいずれであってもよい。一次分散剤と共に二次分散剤を用いることで、分散性をより高めることもできる。 The dispersant of the present invention may be either a primary dispersant (also referred to as a main dispersant or a dispersion stabilizer) or a secondary dispersant (also referred to as a dispersion aid). By using the secondary dispersant together with the primary dispersant, the dispersibility can be further enhanced.
　本発明の分散剤は、ビニル化合物の懸濁重合用分散剤として好適である。本発明の分散剤を用いることで、重合安定性が高まり、平均粒径が小さく且つ粗大粒子の少ない重合体粒子を効率的に得ることができる。また、本発明の分散剤を用いた懸濁重合により得られる重合体粒子は、可塑剤吸収性も良好となる傾向にある。特に本発明の分散剤は、モノマーに対して例えば１，５００ｐｐｍ又は１，０００ｐｐｍ以下といった、使用量が少ない場合にも、平均粒子径が小さくかつ粗大粒子が少なく、可塑剤吸収性が良好な重合体粒子を得ることができる。 The dispersant of the present invention is suitable as a dispersant for suspension polymerization of vinyl compounds. By using the dispersant of the present invention, the polymerization stability is enhanced, and polymer particles having a small average particle size and few coarse particles can be efficiently obtained. Further, the polymer particles obtained by suspension polymerization using the dispersant of the present invention tend to have good plasticizer absorbability. In particular, the dispersant of the present invention has a small average particle size, few coarse particles, and good plasticizer absorbency even when the amount used is small, for example, 1,500 ppm or 1,000 ppm or less with respect to the monomer. Combined particles can be obtained.
　本発明の分散剤は、必要に応じて、懸濁重合に通常使用される防腐剤、防黴剤、ブロッキング防止剤、消泡剤等の添加剤を含んでいてもよい。このような添加剤の含有量は通常、１．０質量％以下である。添加剤は、１種を単独で使用してもよく、２種以上を併用してもよい。 The dispersant of the present invention may contain additives such as preservatives, fungicides, antiblocking agents and antifoaming agents usually used for suspension polymerization, if necessary. The content of such additives is usually 1.0% by mass or less. As the additive, one type may be used alone, or two or more types may be used in combination.
＜ビニル系重合体の製造方法＞
　本発明のビニル重合体の製造方法は、本発明の分散剤の存在下でビニル系化合物を懸濁重合する工程を備える。ビニル系単量体としては、塩化ビニル等のハロゲン化ビニル；酢酸ビニル、プロピオン酸ビニル等のビニルエステル単量体；（メタ）アクリル酸これらのエステル及び塩；マレイン酸、フマル酸、これらのエステル及び無水物；スチレン、アクリロニトリル、塩化ビニリデン、ビニルエーテル等が挙げられる。これらのうち、塩化ビニルを単独で、又は塩化ビニルと共重合することが可能な単量体と共に懸濁重合することが好適である。塩化ビニルと共重合することができる単量体としては、酢酸ビニル、プロピオン酸ビニルなどのビニルエステル単量体；（メタ）アクリル酸メチル、（メタ）アクリル酸エチルなどの（メタ）アクリル酸エステル；エチレン、プロピレンなどのα－オレフィン；無水マレイン酸、イタコン酸などの不飽和ジカルボン酸類；アクリロニトリル、スチレン、塩化ビニリデン、ビニルエーテル等が挙げられる。 <Manufacturing method of vinyl polymer>
The method for producing a vinyl polymer of the present invention comprises a step of suspend-polymerizing a vinyl-based compound in the presence of the dispersant of the present invention. Examples of the vinyl-based monomer include vinyl halides such as vinyl chloride; vinyl ester monomers such as vinyl acetate and vinyl propionate; (meth) acrylic acid esters and salts thereof; maleic acid, fumaric acid, and esters thereof. And anhydrides; styrene, acrylonitrile, vinylidene chloride, vinyl ether and the like. Of these, it is preferable to carry out suspension polymerization of vinyl chloride alone or with a monomer capable of copolymerizing with vinyl chloride. Examples of the monomer that can be copolymerized with vinyl chloride include vinyl ester monomers such as vinyl acetate and vinyl propionate; and (meth) acrylic acid esters such as methyl (meth) acrylate and ethyl (meth) acrylate. Α-olefins such as ethylene and propylene; unsaturated dicarboxylic acids such as maleic anhydride and itaconic acid; acrylonitrile, styrene, vinylidene chloride, vinyl ether and the like.
　前記懸濁重合に使用する媒体としては水性媒体が好ましい。当該水性媒体としては、水、又は水及び有機溶剤を含有するものが挙げられる。前記水性媒体中の水の含有量は、９０質量％以上が好ましい。 An aqueous medium is preferable as the medium used for the suspension polymerization. Examples of the aqueous medium include water or one containing water and an organic solvent. The content of water in the aqueous medium is preferably 90% by mass or more.
　前記懸濁重合する際の水性媒体とビニル系化合物の質量比（水性媒体／ビニル系化合物）は通常０．１～１０であり、０．５～５が好ましく、０．９～２がさらに好ましい。 The mass ratio of the aqueous medium to the vinyl compound (aqueous medium / vinyl compound) at the time of suspension polymerization is usually 0.1 to 10, preferably 0.5 to 5, and more preferably 0.9 to 2. ..
　前記懸濁重合における本発明の分散剤の使用量は特に制限はないが、ビニル系化合物に対して、質量基準で１００ｐｐｍ以上５０，０００ｐｐｍ以下が好ましく、２００ｐｐｍ以上２０，０００ｐｐｍ以下がより好ましく、１０，０００ｐｐｍ以下、５，０００ｐｐｍ以下、２，０００ｐｐｍ以下又は１，５００ｐｐｍ以下がさらに好ましい場合もある。 The amount of the dispersant of the present invention used in the suspension polymerization is not particularly limited, but is preferably 100 ppm or more and 50,000 ppm or less, more preferably 200 ppm or more and 20,000 ppm or less, based on the mass of the vinyl compound. In some cases, 3,000 ppm or less, 5,000 ppm or less, 2,000 ppm or less, or 1,500 ppm or less may be more preferable.
　本発明の分散剤は単独で使用してもよいが、メチルセルロース、ヒドロキシエチルセルロース、ヒドロキシプロピルセルロース、ヒドロキシプロピルメチルセルロースなどの水溶性セルロースエーテル；ポリビニルアルコール、ゼラチンなどの水溶性ポリマー；ソルビタンモノラウレート、ソルビタントリオレート、グリセリントリステアレート、エチレンオキシドプロピレンオキシドブロックコポリマーなどの油溶性乳化剤；ポリオキシエチレンソルビタンモノラウレート、ポリオキシエチレングリセリンオレート、ラウリン酸ナトリウムなどの水溶性乳化剤等と共に使用することもできる。これらは、１種を単独で使用してもよく、２種以上を併用してもよい。 The dispersant of the present invention may be used alone, but water-soluble cellulose ethers such as methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose and hydroxypropyl methyl cellulose; water-soluble polymers such as polyvinyl alcohol and gelatin; sorbitan monolaurate and sorbitan. Oil-soluble emulsifiers such as triolate, glycerin tristearate, ethylene oxide propylene oxide block copolymer; can also be used with water-soluble emulsifiers such as polyoxyethylene sorbitan monolaurate, polyoxyethylene glycerin oleate, sodium laurate and the like. These may be used alone or in combination of two or more.
　ビニル系化合物の懸濁重合には、従来から塩化ビニル単量体等の重合に使用されている、油溶性又は水溶性の重合開始剤を用いることができる。油溶性の重合開始剤としては、例えば、ジイソプロピルペルオキシジカーボネート、ジ（２－エチルヘキシル）ペルオキシジカーボネート、ジエトキシエチルペルオキシジカーボネート等のペルオキシジカーボネート化合物；ｔ－ブチルペルオキシネオデカネート、ｔ－ブチルペルオキシピバレート、ｔ－ヘキシルペルオキシピバレート、α－クミルペルオキシネオデカネート等のパーエステル化合物；アセチルシクロヘキシルスルホニルペルオキシド、２，４，４－トリメチルペンチル－２－ペルオキシフェノキシアセテート、３，５，５－トリメチルヘキサノイルペルオキシド、ラウロイルペルオキシド等の過酸化物；アゾビス－２，４－ジメチルバレロニトリル、アゾビス（４－２，４－ジメチルバレロニトリル）等のアゾ化合物等が挙げられる。水溶性の重合開始剤としては、例えば過硫酸カリウム、過硫酸アンモニウム、過酸化水素、クメンハイドロペルオキシド等が挙げられる。これらの油溶性或いは水溶性の重合開始剤は１種を単独で、又は２種以上を組合せて用いることができる。 For suspension polymerization of vinyl compounds, an oil-soluble or water-soluble polymerization initiator that has been conventionally used for polymerization of vinyl chloride monomers and the like can be used. Examples of the oil-soluble polymerization initiator include peroxydicarbonate compounds such as diisopropylperoxydicarbonate, di (2-ethylhexyl) peroxydicarbonate, and diethoxyethylperoxydicarbonate; t-butylperoxyneodecanate and t-butyl. Perester compounds such as peroxypivalate, t-hexyl peroxypivalate, α-cumylperoxyneodecanate; acetylcyclohexylsulfonyl peroxide, 2,4,4-trimethylpentyl-2-peroxyphenoxyacetate, 3,5,5 -Peroxides such as trimethylhexanoyl peroxide and lauroyl peroxide; azo compounds such as azobis-2,4-dimethylvaleronitrile and azobis (4-2,4-dimethylvaleronitrile) can be mentioned. Examples of the water-soluble polymerization initiator include potassium persulfate, ammonium persulfate, hydrogen peroxide, cumene hydroperoxide and the like. These oil-soluble or water-soluble polymerization initiators may be used alone or in combination of two or more.
　ビニル系化合物の懸濁重合に際し、必要に応じて、重合反応系にその他の各種添加剤を加えることができる。添加剤としては、例えば、アルデヒド類、ハロゲン化炭化水素類、メルカプタン類などの重合調節剤、フェノール化合物、硫黄化合物、Ｎ－オキシド化合物などの重合禁止剤などが挙げられる。また、ｐＨ調整剤、架橋剤なども任意に加えることができる。 In suspension polymerization of vinyl compounds, various other additives can be added to the polymerization reaction system as needed. Examples of the additive include polymerization inhibitors such as aldehydes, halogenated hydrocarbons and mercaptans, and polymerization inhibitors such as phenol compounds, sulfur compounds and N-oxide compounds. Further, a pH adjuster, a cross-linking agent and the like can be arbitrarily added.
　ビニル系化合物の懸濁重合に際し、重合温度には特に制限はなく、２０℃程度の低い温度であっても、９０℃を超える高い温度であってもよい。また、重合反応系の除熱効率を高めるために、リフラックスコンデンサー付の重合器を用いることも好ましい実施形態の一つである。 In suspension polymerization of a vinyl compound, the polymerization temperature is not particularly limited, and may be a low temperature of about 20 ° C. or a high temperature of over 90 ° C. Further, in order to increase the heat removal efficiency of the polymerization reaction system, it is also one of the preferable embodiments to use a polymerizer with a reflux capacitor.
　本発明のビニル系重合体の製造方法において、一次分散剤（例えば本発明の分散剤）及び二次分散剤（例えば本発明の分散剤）の添加量の質量比（一次分散剤／二次分散剤）は、用いられる分散剤の種類等によって異なるが、例えば９５／５～２０／８０の範囲が好ましく、９０／１０～３０／７０の範囲がより好ましい。一次分散剤と二次分散剤とは、重合の初期に一括して添加してもよいし、重合の途中で分割して添加してもよい。 In the method for producing a vinyl-based polymer of the present invention, the mass ratio of the amount of the primary dispersant (for example, the dispersant of the present invention) and the secondary dispersant (for example, the dispersant of the present invention) added (primary dispersant / secondary dispersion). The agent) varies depending on the type of dispersant used and the like, but is preferably in the range of 95/5 to 20/80, more preferably in the range of 90/10 to 30/70. The primary dispersant and the secondary dispersant may be added collectively at the initial stage of the polymerization, or may be added separately in the middle of the polymerization.
　以下、実施例を示して本発明をさらに具体的に説明するが、本発明はこれらの例によって限定されるものではない。なお、「部」、「％」、「ｐｐｍ」とあるのは、特に断りのない限り、質量基準を意味する。 Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. The terms "part", "%", and "ppm" mean mass standards unless otherwise specified.
［ＰＶＡの粘度平均重合度］
　ＰＶＡの粘度平均重合度はＪＩＳ　Ｋ　６７２６：１９９４に準じて測定した。具体的には、ＰＶＡのけん化度が９９．５モル％未満の場合には、けん化度９９．５モル％以上になるまで再けん化し、得られたＰＶＡについて、水中、３０℃で測定した極限粘度［η］（リットル／ｇ）を用いて下記式（１１）により粘度平均重合度を求めた。
　粘度平均重合度＝（［η］×１０４／８．２９）（１／０．６２）　（１１） [Viscosity average degree of polymerization of PVA]
The viscosity average degree of polymerization of PVA was measured according to JIS K 6726: 1994. Specifically, when the saponification degree of PVA is less than 99.5 mol%, it is re-saponified until the saponification degree becomes 99.5 mol% or more, and the obtained PVA is measured in water at 30 ° C. to the limit. Using the viscosity [η] (liter / g), the viscosity average degree of polymerization was determined by the following formula (11).
Viscosity average degree of polymerization = ([η] × 10 4 / 8.29) (1 / 0.62) (11)
［ＰＶＡのけん化度］
　ＰＶＡのけん化度は、ＪＩＳ　Ｋ　６７２６：１９９４に記載の方法により求めた。 [Saponification degree of PVA]
The degree of saponification of PVA was determined by the method described in JIS K 6726: 1994.
［ＰＶＡ水溶液の吸光度］
　０．１質量％のＰＶＡ水溶液を調製し、（株）島津製作所製吸光光度計「ＵＶ２４５０」を用いて３２０ｎｍの吸光度（光路長１０ｍｍ）を測定した。 [Absorbance of PVA aqueous solution]
A 0.1% by mass PVA aqueous solution was prepared, and the absorbance at 320 nm (optical path length 10 mm) was measured using an absorptiometer "UV2450" manufactured by Shimadzu Corporation.
［ＨＳＰ距離（合成例１～１１、１７～１９）］
　下記の方法により、ＨＳＰ距離［Ｒａ，１］（（Ｊ／ｃｍ３）１／２）及びＨＳＰ距離［Ｒａ，２］（（Ｊ／ｃｍ３）１／２）を算出した。
　まず、ＰＶＡをけん化度９９．５モル％以上まで再けん化後、メタノールで洗浄した。得られたＰＶＡの１質量％Ｄ２Ｏ溶液（内部標準として０．１質量％トリメチルシリルプロパン酸を添加）をサンプルとして用いて、１Ｈ－ＮＭＲ測定を行った（４００ＭＨｚ、８０℃、積算２５６回）。変性剤として直鎖アルキルアルデヒドを用いた場合、前記式（１）で表される構造として、下記式（４）で表される構造が形成される。そして、式（４）中のｍは、１Ｈ－ＮＭＲ測定の結果から、下記式（１３）により求められる。
　－（Ｃ＝Ｏ）－（ＣＨ２）ｍ－ＣＨ３　　　　　（４）
　ｍ＝｛（ピーク（ａ）の積分値）×３｝／｛（ピーク（ｂ）の積分値）×２｝＋２　　（１３）
　式（１３）中、ピーク（ａ）は、１．２２～１．３８ｐｐｍの間に存在するアルキル鎖のメチレンに由来するピークを表し、ピーク（ｂ）は、０．８０～０．９２ｐｐｍの間に存在するアルキル鎖のメチルに由来するピークを表す。ピーク（ｂ）が存在せず、０．９４～１．０８ｐｐｍ付近にピークが存在する場合はｍ＝１とし、ピーク（ａ）もピーク（ｂ）も存在しない場合はｍ＝０とした。
　１Ｈ－ＮＭＲスペクトルから得られた構造をもとに、前記式（５）～（１０）を用いて、ＨＳＰ距離［Ｒａ，１］及びＨＳＰ距離［Ｒａ，２］を算出した。 [HSP distance (synthesis examples 1 to 11, 17 to 19)]
The HSP distance [R a, 1 ] ((J / cm 3 ) 1/2 ) and the HSP distance [R a, 2 ] ((J / cm 3 ) 1/2 ) were calculated by the following methods.
First, PVA was re-saponified to a saponification degree of 99.5 mol% or more, and then washed with methanol. Using the obtained 1% by mass D2O solution of PVA (with 0.1% by mass trimethylsilylpropanoic acid added as an internal standard) as a sample, 1 H - NMR measurement was performed (400 MHz, 80 ° C., total 256 times). ). When a linear alkyl aldehyde is used as the denaturing agent, the structure represented by the following formula (4) is formed as the structure represented by the above formula (1). Then, m in the formula (4) is obtained by the following formula (13) from the result of 1 H-NMR measurement.
-(C = O)-(CH 2 ) m -CH 3 (4)
m = {(integral value of peak (a)) × 3} / {(integral value of peak (b)) × 2} + 2 (13)
In the formula (13), the peak (a) represents a peak derived from methylene of the alkyl chain existing between 1.22 and 1.38 ppm, and the peak (b) is between 0.80 and 0.92 ppm. Represents a peak derived from the methyl of the alkyl chain present in. When the peak (b) does not exist and the peak exists in the vicinity of 0.94 to 1.08 ppm, m = 1 is set, and when neither the peak (a) nor the peak (b) exists, m = 0.
1 Based on the structure obtained from the 1 H-NMR spectrum, the HSP distance [ Ra, 1 ] and the HSP distance [ Ra, 2 ] were calculated using the above equations (5) to (10).
［ＨＳＰ距離（合成例１２、１３：参考値）］
　後述するように、合成例１２においては１－ヘキセンを、合成例１３においては１－デセンを変性剤として用いた。このとき得られるＰＶＡは、側鎖にアルキル基を有する。アルキル基と塩化ビニル又は水とのＨＳＰ距離［Ｒｂ］を参考値として算出した。具体的には、下記の方法によりＲｂを算出した。
　前記と同様の方法で１Ｈ－ＮＭＲ測定を行った。変性剤としてα－オレフィンを用いた場合は、ＰＶＡに導入された変性剤に由来する下記式（１４）で表される構造中のｎは、下記式（１５）により求められる。
　－（ＣＨ２）ｎ－ＣＨ３　　（１４）
　ｎ＝｛（ピーク（ｃ）の積分値／２）／｛ピーク（ｄ）の積分値｝／３｝　　（１５）
　式（１５）中、ピーク（ｃ）は、１．１～１．３ｐｐｍの間に存在するピークを表し、ピーク（ｄ）は、０．８０～０．９２ｐｐｍの間に存在するピークを表す。
　続いて、ＨＳＰ距離を算出した。式（１４）で表される構造のモル体積は、下記式（１６）により算出でき、ＨＳＰ値は、下記式（１７）～（１９）で算出できる。
　Ｖ＝３３．５＋ｎ×１６．１　　（１６）
　δｄ＝（４２０＋ｎ×２７０）／Ｖ　　（１７）
　δｐ＝０　　（１８）
　δｈ＝０　　（１９）
　続いて、Ｒｂを下記式（２０）を用いて計算した。塩化ビニルモノマーのＨＳＰ値は、（δＤ、δＰ、δＨ）＝（１５．４、８．１、２．４）とし、水のＨＳＰ値は（δＤ、δＰ、δＨ）＝（１５．５、１６．０、４２．４）とした。
　Ｒｂ＝｛４（δＤ－δｄ）２＋（δＰ－δｐ）２＋（δＨ－δｈ）２｝１／２　　（２０） [HSP distance (synthesis examples 12, 13: reference value)]
As will be described later, 1-hexene was used as a denaturing agent in Synthetic Example 12, and 1-decene was used as a denaturing agent in Synthetic Example 13. The PVA obtained at this time has an alkyl group in the side chain. The HSP distance [R b ] between the alkyl group and vinyl chloride or water was used as a reference value. Specifically, R b was calculated by the following method.
1 1 H-NMR measurement was carried out by the same method as above. When α-olefin is used as the denaturing agent, n in the structure represented by the following formula (14) derived from the denaturing agent introduced into PVA is obtained by the following formula (15).
-(CH 2 ) n -CH 3 (14)
n = {(integral value of peak (c) / 2) / {integral value of peak (d)} / 3} (15)
In the formula (15), the peak (c) represents a peak existing between 1.1 and 1.3 ppm, and the peak (d) represents a peak existing between 0.80 and 0.92 ppm.
Subsequently, the HSP distance was calculated. The molar volume of the structure represented by the formula (14) can be calculated by the following formula (16), and the HSP value can be calculated by the following formulas (17) to (19).
V = 33.5 + n × 16.1 (16)
δd = (420 + n × 270) / V (17)
δp = 0 (18)
δh = 0 (19)
Subsequently, R b was calculated using the following equation (20). The HSP value of the vinyl chloride monomer is (δD, δP, δH) = (15.4, 8.1, 2.4), and the HSP value of water is (δD, δP, δH) = (15.5, 16). It was set to 0.0, 42.4).
R b = {4 (δD-δd) 2 + (δP-δp) 2 + (δH-δh) 2 } 1/2 (20)
［ＨＳＰ距離（合成例１４、１５：参考値）］
　後述するように、合成例１４においては１－オクタンチオールを、合成例１５においては１－ヘキサンチオールを変性剤として用いた。このとき得られるＰＶＡは、末端にアルキルチオール基を有する。アルキルチオール基と塩化ビニル又は水とのＨＳＰ距離を、山本秀樹著「ＳＰ値：基礎・応用と計算方法」（２００５年発行、情報機構）及びＪ．　Ｂｒａｎｄｒｕｐ著「ＰＯＬＹＭＥＲ　ＨＡＮＤＢＯＯＫ（ＦＯＵＲＴＨ　ＥＤＩＴＩＯＮ）」（２００３年発行、Ｗｉｌｅｙ）に記載の方法に基づき、上述した方法と同様にして、参考値として算出した。 [HSP distance (synthesis examples 14, 15: reference value)]
As will be described later, 1-octanethiol was used as a denaturing agent in Synthesis Example 14, and 1-hexanethiol was used as a denaturing agent in Synthesis Example 15. The PVA obtained at this time has an alkylthiol group at the terminal. The HSP distance between the alkylthiol group and vinyl chloride or water was described by Hideki Yamamoto, "SP Value: Basics, Applications and Calculation Methods" (2005, Information Organization) and J. Mol. It was calculated as a reference value in the same manner as the above-mentioned method based on the method described in "POLYMER HANDBOOK" (published in 2003, Wiley) by Brandrup.
［変性率］
　ＰＶＡの全構造単位に対する変性剤により変性された単位の含有率（モル％）を「変性率」と称する。なお、変性剤により変性された単位が式（１）で表される構造であるとき、変性率は、ビニルアルコール系重合体の全構造単位に対する式（１）で表される構造の含有率［Ｘ］（モル％）と同義である。
　１Ｈ－ＮＭＲ測定を行い、変性率（モル％）を算出した。ＰＶＡをけん化度９９．５モル％以上まで再けん化後、メタノールで洗浄した。得られたＰＶＡの１質量％Ｄ２Ｏ溶液（内部標準として０．１質量％トリメチルシリルプロパン酸を添加）をサンプルとして用いて、１Ｈ－ＮＭＲ測定を行った（４００ＭＨｚ、８０℃、積算２５６回）。ＰＶＡの主鎖のメチン基に由来するピークの積分値［Ｍ］、変性剤に由来する構造に含まれるメチル基に由来するピークの積分値［Ｏ］及び変性剤１分子当たりのメチル基の数ｑを用いて、下記式（２１）により、変性率（モル％）を求めた。なお、ＰＶＡの主鎖のメチン基に由来するピークは３．８～４．０ｐｐｍに存在する。また、変性剤に由来する構造に含まれるメチル基に由来するピークは、変性剤が例えば炭素数４以上の直鎖アルキルアルデヒドの場合、０．８０～０．９２ｐｐｍに存在する。
　変性率（モル％）＝｛（［Ｏ］／（３×ｑ））／［Ｍ］｝×１００　　（２１） [Denaturation rate]
The content (mol%) of the unit modified by the modifying agent with respect to all the structural units of PVA is referred to as "modification rate". When the unit modified by the modifying agent has a structure represented by the formula (1), the modification rate is the content of the structure represented by the formula (1) with respect to all the structural units of the vinyl alcohol polymer. It is synonymous with X] (mol%).
1 1 H-NMR measurement was performed and the denaturation rate (mol%) was calculated. PVA was re-saponified to a saponification degree of 99.5 mol% or more, and then washed with methanol. Using the obtained 1% by mass D2O solution of PVA (with 0.1% by mass trimethylsilylpropanoic acid added as an internal standard) as a sample, 1 H - NMR measurement was performed (400 MHz, 80 ° C., total 256 times). ). The integrated value [M] of the peak derived from the methine group of the main chain of PVA, the integrated value [O] of the peak derived from the methyl group contained in the structure derived from the denaturant, and the number of methyl groups per molecule of the denaturant. Using q, the modification rate (mol%) was determined by the following formula (21). The peak derived from the methine group of the main chain of PVA exists at 3.8 to 4.0 ppm. Further, the peak derived from the methyl group contained in the structure derived from the modifier exists at 0.80 to 0.92 ppm when the modifier is, for example, a linear alkylaldehyde having 4 or more carbon atoms.
Degeneration rate (mol%) = {([O] / (3 × q)) / [M]} × 100 (21)
［合成例１］（ＰＶＡ－１の製造）
　撹拌機、還流冷却管、窒素導入管及び重合開始剤の添加口を備えた反応器に、酢酸ビニル１０００質量部及び１－オクタナール２１．５質量部を仕込み、窒素バブリングをしながら３０分間系内を窒素置換した。反応器の昇温を開始し、内温が６０℃となったところで、２，２’－アゾビスイソブチロニトリル（ＡＩＢＮ）１．１質量部を添加し重合を開始した。６０℃で３時間重合した後、冷却して重合を停止した。重合停止時の固形分濃度は５１．２質量％、重合率５０％であった。続いて、３０℃、減圧下でメタノールを時々添加しながら未反応の単量体の除去を行い、ビニルエステル系重合体のメタノール溶液（濃度３４．５質量％）を得た。次に、このメタノール溶液にさらにメタノールを加えて調製したビニルエステル系重合体のメタノール溶液１７４．６質量部（溶液中の前記重合体６０質量部）に、水酸化ナトリウムの１０％メタノール溶液３．７質量部、酢酸メチル２０質量部及びイオン交換水２．０質量部を添加して、４０℃でけん化を行った（けん化溶液の前記重合体濃度３０質量％、前記重合体中の酢酸ビニル単位に対する水酸化ナトリウムのモル比０．０１３、けん化溶液の含水率１質量％）。水酸化ナトリウムのメタノール溶液を添加後、約１２分でゲル状物が生成したので、これを粉砕器にて粉砕した。さらに４０℃で１時間放置してけん化を進行させた後、酢酸メチル１６０質量部とメタノール４０質量部を加えて、４０℃で３０分間放置洗浄した。この洗浄操作を２回繰り返した後、脱液して得られた白色固体を４０℃で真空乾燥を１６時間行い、ＰＶＡ（ＰＶＡ－１）を得た。ＰＶＡ－１の物性を表２に示す。
　ＰＶＡ―１をソックスレー抽出器を用いて酢酸メチルで十分に洗浄し４０℃で１６時間真空乾燥した。洗浄後ＰＶＡ－１の１質量％ＤＭＳＯ溶液（内部標準として０．０５容積％テトラメチルシランを添加）をサンプルとして用いて、１Ｈ－ＮＭＲ測定を行った（４００ＭＨｚ、８０℃、積算２５６回）。この結果を元にＰＶＡ－１における全構造単位に対するホルミル基の含有率を求めたところ、３．０ミリモル％以下であった。 [Synthesis Example 1] (Production of PVA-1)
1000 parts by mass of vinyl acetate and 21.5 parts by mass of 1-octanal were charged in a reactor equipped with a stirrer, a reflux condenser, a nitrogen introduction tube and an addition port for a polymerization initiator, and the system was charged with nitrogen bubbling for 30 minutes. Was replaced with nitrogen. The temperature of the reactor was started to rise, and when the internal temperature reached 60 ° C., 1.1 parts by mass of 2,2'-azobisisobutyronitrile (AIBN) was added to start polymerization. After polymerizing at 60 ° C. for 3 hours, the mixture was cooled to terminate the polymerization. The solid content concentration at the time of stopping the polymerization was 51.2% by mass and the polymerization rate was 50%. Subsequently, the unreacted monomer was removed by occasionally adding methanol at 30 ° C. under reduced pressure to obtain a methanol solution (concentration: 34.5% by mass) of the vinyl ester polymer. Next, a 10% methanol solution of sodium hydroxide was added to 174.6 parts by mass (60 parts by mass of the polymer in the solution) of a vinyl ester-based polymer prepared by further adding methanol to this methanol solution. 7 parts by mass, 20 parts by mass of methyl acetate and 2.0 parts by mass of ion-exchanged water were added and saponified at 40 ° C. (the polymer concentration of the saponified solution was 30% by mass, the vinyl acetate unit in the polymer). The molar ratio of sodium hydroxide to 0.013, the water content of the saponification solution was 1% by mass). About 12 minutes after adding the methanol solution of sodium hydroxide, a gel-like substance was formed, which was pulverized with a pulverizer. After further allowing it to stand at 40 ° C. for 1 hour to promote saponification, 160 parts by mass of methyl acetate and 40 parts by mass of methanol were added, and the mixture was left to wash at 40 ° C. for 30 minutes. After repeating this washing operation twice, the white solid obtained by deliquessing was vacuum dried at 40 ° C. for 16 hours to obtain PVA (PVA-1). The physical characteristics of PVA-1 are shown in Table 2.
PVA-1 was thoroughly washed with methyl acetate using a Soxhlet extractor and vacuum dried at 40 ° C. for 16 hours. After washing, 1 H-NMR measurement was performed using a 1% by mass DMSO solution of PVA-1 (added 0.05% by volume tetramethylsilane as an internal standard) as a sample (400 MHz, 80 ° C., total 256 times). .. Based on this result, the content of formyl groups in PVA-1 with respect to all structural units was determined and found to be 3.0 mmol% or less.
［合成例２～８、１０～１３、１７、１９］（ＰＶＡ－２～８、１０～１３、１７、１９の製造）
　酢酸ビニル及びメタノールの仕込み量、重合時に使用する変性剤の種類や添加量等の重合条件；けん化時におけるビニルエステル重合体の濃度、酢酸ビニル単位に対する水酸化ナトリウムのモル比等のけん化条件を表１に示すように示すように変更したこと以外は、合成例１と同様の方法により各ＰＶＡ（ＰＶＡ－２～８、１０～１３、１７、１９）を製造した。なお、ＰＶＡ－８は、ＰＶＡ－８ＡとＰＶＡ－８Ｂの各ポリ酢酸ビニルメタノール溶液を６：４で混合した後、けん化を行った。ＰＶＡ－２～８、１０～１３、１７、１９の物性を表２に示す。 [Synthesis Examples 2-8, 10-13, 17, 19] (Production of PVA-2-8, 10-13, 17, 19)
Polymerization conditions such as the amount of vinyl acetate and methanol charged, the type and amount of modifier used during polymerization; the concentration of vinyl ester polymer at the time of saponification, and the saponification conditions such as the molar ratio of sodium hydroxide to vinyl acetate units are shown. Each PVA (PVA-2 to 8, 10 to 13, 17, 19) was produced by the same method as in Synthesis Example 1 except that the changes were made as shown in 1. PVA-8 was saponified after mixing each polyvinyl acetate methanol solution of PVA-8A and PVA-8B at a ratio of 6: 4. Table 2 shows the physical properties of PVA-2 to 8, 10 to 13, 17, and 19.
［合成例１４の製造］（ＰＶＡ－１４）
　撹拌機、還流冷却管、窒素導入管、連鎖移動剤滴下口及び重合開始剤の添加口を備えた反応器に、酢酸ビニル１２００質量部及び１－オクタンチオール０．１８質量部を仕込み、窒素バブリングをしながら３０分間系内を窒素置換した。また１－オクタンチオールのメタノール溶液（濃度１．８質量％）を窒素ガスのバブリングにより窒素置換した。反応器の昇温を開始し、内温が６０℃となったところで、２，２’－アゾビスイソブチロニトリル（ＡＩＢＮ）０．７５質量部を添加し重合を開始した。前記反応器に、前記１－オクタンチオールのメタノール溶液を滴下して重合溶液中の単量体組成比を一定に保ちながら、６０℃で２時間重合した後、冷却して重合を停止した。重合停止時の固形分濃度は３９．４質量％、重合率は４０％であった。また、添加した１－オクタンチオールは、当初仕込み量とあわせて２．０５質量部であった。続いて、３０℃、減圧下でメタノールを時々添加しながら未反応の単量体の除去を行い、ビニルエステル系重合体のメタノール溶液（濃度３８．２質量％）を得た。次に、このメタノール溶液にさらにメタノールを加えて調製したビニルエステル系重合体のメタノール溶液１７５．８質量部（溶液中の前記重合体６０質量部）に、水酸化ナトリウムの１０％メタノール溶液２．５質量部、酢酸メチル２０質量部及びイオン交換水２．０質量部を添加して、４０℃でけん化を行った（けん化溶液の前記重合体濃度２５質量％、前記重合体中の酢酸ビニル単位に対する水酸化ナトリウムのモル比０．００７５、けん化溶液の含水率１質量％）。水酸化ナトリウムのメタノール溶液を添加後約１０分でゲル状物が生成したので、これを粉砕器にて粉砕し、さらに４０℃で１時間放置してけん化を進行させた後、酢酸メチル１６０質量部とメタノール４０質量部を加えて、４０℃で３０分間放置洗浄した。この洗浄操作を２回繰り返した後、脱液して得られた白色固体を４０℃で真空乾燥を１６時間行い、ＰＶＡ（ＰＶＡ－１４）を得た。ＰＶＡ－１４の物性を表２に示す。 [Manufacturing of Synthesis Example 14] (PVA-14)
A reactor equipped with a stirrer, a reflux cooling tube, a nitrogen introduction tube, a chain transfer agent dropping port and a polymerization initiator addition port is charged with 1200 parts by mass of vinyl acetate and 0.18 parts by mass of 1-octanethiol, and nitrogen bubbling. The inside of the system was replaced with nitrogen for 30 minutes. Further, a methanol solution of 1-octanethiol (concentration: 1.8% by mass) was replaced with nitrogen by bubbling nitrogen gas. The temperature of the reactor was started to rise, and when the internal temperature reached 60 ° C., 0.75 parts by mass of 2,2'-azobisisobutyronitrile (AIBN) was added to start polymerization. The 1-octanethiol methanol solution was added dropwise to the reactor, and the polymerization was carried out at 60 ° C. for 2 hours while keeping the monomer composition ratio in the polymerization solution constant, and then cooled to terminate the polymerization. The solid content concentration at the time of stopping the polymerization was 39.4% by mass, and the polymerization rate was 40%. The amount of 1-octanethiol added was 2.05 parts by mass including the initially charged amount. Subsequently, the unreacted monomer was removed by occasionally adding methanol at 30 ° C. under reduced pressure to obtain a methanol solution (concentration: 38.2% by mass) of the vinyl ester polymer. Next, a 10% methanol solution of sodium hydroxide was added to 175.8 parts by mass (60 parts by mass of the polymer in the solution) of a vinyl ester-based polymer prepared by further adding methanol to this methanol solution. 5 parts by mass, 20 parts by mass of methyl acetate and 2.0 parts by mass of ion-exchanged water were added and saponified at 40 ° C. (25% by mass of the polymer concentration in the saponification solution, vinyl acetate unit in the polymer). The molar ratio of sodium hydroxide to 0.0075, the water content of the saponification solution was 1% by mass). A gel-like substance was formed about 10 minutes after the addition of the methanol solution of sodium hydroxide. The gel was crushed with a crusher and left at 40 ° C. for 1 hour to promote saponification, and then 160 mass of methyl acetate. A portion and 40 parts by mass of methanol were added, and the mixture was washed at 40 ° C. for 30 minutes. After repeating this washing operation twice, the white solid obtained by deliquessing was vacuum dried at 40 ° C. for 16 hours to obtain PVA (PVA-14). The physical characteristics of PVA-14 are shown in Table 2.
［合成例１５の製造］（ＰＶＡ－１５）
　酢酸ビニル及びメタノールの仕込み量、変性剤の種類や添加量等の重合条件；けん化時におけるビニルエステル重合体の濃度、酢酸ビニル単位に対する水酸化ナトリウムのモル比等のけん化条件を表１に示すように示すように変更したこと以外は、合成例１４と同様の方法によりＰＶＡ（ＰＶＡ－１５）を製造した。ＰＶＡ－１５の物性を表２に示す。 [Manufacturing of Synthesis Example 15] (PVA-15)
Polymerization conditions such as the amount of vinyl acetate and methanol charged, the type and amount of modifier added; the saponification conditions such as the concentration of the vinyl ester polymer at the time of saponification and the molar ratio of sodium hydroxide to vinyl acetate units are shown in Table 1. PVA (PVA-15) was produced by the same method as in Synthesis Example 14, except that the changes were made as shown in. The physical characteristics of PVA-15 are shown in Table 2.
［合成例１６の製造］（ＰＶＡ－１６）
　酢酸ビニル及びメタノールの仕込み量、変性剤を使用しないこと等の重合条件；けん化時におけるビニルエステル重合体の濃度、酢酸ビニル単位に対する水酸化ナトリウムのモル比等のけん化条件を表１に示すように示すように変更したこと以外は、合成例１と同様の方法によりＰＶＡ（ＰＶＡ－１６）を製造した。ＰＶＡ－１６の物性を表２に示す。 [Manufacturing of Synthesis Example 16] (PVA-16)
Polymerization conditions such as the amount of vinyl acetate and methanol charged, the use of no modifier, etc .; the saponification conditions such as the concentration of the vinyl ester polymer at the time of saponification and the molar ratio of sodium hydroxide to vinyl acetate units are shown in Table 1. PVA (PVA-16) was produced by the same method as in Synthesis Example 1 except that it was modified as shown. The physical characteristics of PVA-16 are shown in Table 2.
［合成例９、１８の製造］（ＰＶＡ－９、１８）
　合成例９では、ＰＶＡ－１を１３０℃で１時間熱処理を行い、ＰＶＡ－９を合成した。また、合成例１８では、ＰＶＡ－１７を１３０℃で１時間熱処理を行い、ＰＶＡ－１８を合成した。ＰＶＡ－９、１８の物性を表２に示す。 [Production of Synthesis Examples 9 and 18] (PVA-9, 18)
In Synthesis Example 9, PVA-1 was heat-treated at 130 ° C. for 1 hour to synthesize PVA-9. Further, in Synthesis Example 18, PVA-17 was heat-treated at 130 ° C. for 1 hour to synthesize PVA-18. The physical characteristics of PVA-9 and 18 are shown in Table 2.
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000005
Figure JPOXMLDOC01-appb-T000005
［実施例１］
　得られたＰＶＡ－１を懸濁重合用分散剤として用いて、下記の方法で塩化ビニルの懸濁重合を行った。次いで、得られた塩化ビニル重合体粒子について、平均粒子径、粗大粒子量及び可塑剤吸収性の評価を行った。評価結果を表３に示す。 [Example 1]
Using the obtained PVA-1 as a dispersant for suspension polymerization, suspension polymerization of vinyl chloride was carried out by the following method. Next, the obtained vinyl chloride polymer particles were evaluated for average particle size, coarse particle amount, and plasticizer absorbability. The evaluation results are shown in Table 3.
（塩化ビニルの懸濁重合）
　前記で得られたビニルアルコール系共重合体を、塩化ビニルに対して１０００ｐｐｍに相当する量となるように脱イオン水に溶解させ、分散剤水溶液を調製した。このようにして得られた分散剤水溶液１１５０ｇを、容量５Ｌのオートクレーブに仕込んだ。次いでオートクレーブにクミルパーオキシネオデカノエートの７０％トルエン溶液０．６５ｇ及びｔ－ブチルパーオキシネオデカノエートの７０％トルエン溶液１．０５ｇを仕込んだ。オートクレーブ内の圧力が０．００６７ＭＰａになるまで脱気して酸素を除いた。その後、塩化ビニル８００ｇを仕込み、オートクレーブ内の内容物を５７℃に昇温して、撹拌下に重合を開始した。重合開始時におけるオートクレーブ内の圧力は０．８３ＭＰａであった。重合を開始してから３．５時間が経過し、オートクレーブ内の圧力が０．７０ＭＰａとなった時点で重合を停止し、未反応の塩化ビニルを除去した。その後、重合スラリーを取り出し、６５℃にて１７時間乾燥を行い、塩化ビニル重合体粒子を得た。 (Suspension polymerization of vinyl chloride)
The vinyl alcohol-based copolymer obtained above was dissolved in deionized water so as to have an amount corresponding to 1000 ppm with respect to vinyl chloride to prepare an aqueous dispersant solution. 1150 g of the dispersant aqueous solution thus obtained was charged into an autoclave having a capacity of 5 L. The autoclave was then charged with 0.65 g of a 70% toluene solution of cumylperoxyneodecanoate and 1.05 g of a 70% toluene solution of t-butylperoxyneodecanoate. Oxygen was removed by degassing until the pressure in the autoclave reached 0.0067 MPa. Then, 800 g of vinyl chloride was charged, the temperature of the contents in the autoclave was raised to 57 ° C., and polymerization was started under stirring. The pressure in the autoclave at the start of polymerization was 0.83 MPa. When 3.5 hours had passed from the start of the polymerization and the pressure in the autoclave reached 0.70 MPa, the polymerization was stopped and unreacted vinyl chloride was removed. Then, the polymerized slurry was taken out and dried at 65 ° C. for 17 hours to obtain vinyl chloride polymer particles.
（塩化ビニル重合体粒子の評価）
（１）塩化ビニル重合体粒子の平均粒子径
　タイラーメッシュ基準の金網を使用して、乾式篩分析により粒度分布を測定し、その結果をロジン・ラムラー（Ｒｏｓｉｎ－Ｒａｍｍｌｅｒ）分布式にプロットして平均粒子径（ｄｐ５０；メジアン径）を算出した。 (Evaluation of vinyl chloride polymer particles)
(1) Average particle size of vinyl chloride polymer particles Using a wire mesh based on Tyler mesh, the particle size distribution was measured by dry sieve analysis, and the results were plotted in the Rosin-Rammler distribution formula and averaged. The particle size (d p50 ; median size) was calculated.
（２）粗大粒子量
　目開き２５０μｍの篩（ＪＩＳ標準篩のメッシュ換算では、６０メッシュ）を通過しなかった塩化ビニル重合体粒子の含有量を質量％で表示した。数字が小さいほど粗大粒子が少なく、粒度分布がシャープであり、重合安定性に優れていることを示している。 (2) Amount of coarse particles The content of vinyl chloride polymer particles that did not pass through a sieve having an opening of 250 μm (60 mesh in terms of mesh of JIS standard sieve) was displayed in% by mass. The smaller the number, the smaller the number of coarse particles, the sharper the particle size distribution, and the better the polymerization stability.
（３）可塑剤吸収性（ＣＰＡ）
　脱脂綿を０．０２ｇ詰めた容量５ｍＬのシリンジの質量を量り（Ａ（ｇ）とする）、そこに塩化ビニル重合体粒子０．５ｇを入れ質量を量り（Ｂ（ｇ）とする）、そこにジオクチルフタレート（ＤＯＰ）１ｇを入れ１５分静置後、３０００ｒｐｍ、４０分遠心分離して質量を量った（Ｃ（ｇ）とする）。そして、下記式（２２）により可塑剤吸収性（％）を求めた。可塑剤吸収性が高いほど、加工が容易で主にシートへの加工時にブツ等の外観に生じる欠点を生じにくいことを示す。なお、重合が不安定で平均粒子径や粗大粒子量が多い場合、可塑剤吸収性が高くなるが、これは重合体粒子の空隙率によるものではない。本評価において、平均粒子径が１８０μｍより小さいときの可塑剤吸収性が２７％以上のとき可塑剤吸収性は良好とし、２９％以上のとき可塑剤吸収性がより良好と判断した。
　可塑剤吸収性（％）＝１００×［｛（Ｃ－Ａ）／（Ｂ－Ａ）｝－１］　　（２２） (3) Plasticizer absorbency (CPA)
Weigh a 5 mL syringe filled with 0.02 g of cotton wool (referred to as A (g)), put 0.5 g of vinyl chloride polymer particles into it, and weigh it (referred to as B (g)). After 1 g of dioctylphthalate (DOP) was added and allowed to stand for 15 minutes, the mixture was centrifuged at 3000 rpm for 40 minutes and weighed (referred to as C (g)). Then, the plasticizer absorbability (%) was determined by the following formula (22). It is shown that the higher the plasticizer absorbency, the easier the processing and the less likely it is that defects such as lumps occur in the appearance when the sheet is processed. When the polymerization is unstable and the average particle size and the amount of coarse particles are large, the plasticizer absorbability becomes high, but this is not due to the porosity of the polymer particles. In this evaluation, when the average particle size is smaller than 180 μm, the plasticizer absorbability is judged to be good when the plasticizer absorbability is 27% or more, and when the average particle size is 29% or more, the plasticizer absorbability is judged to be better.
Plasticizer absorbency (%) = 100 × [{(CA) / (BA)} -1] (22)
［実施例２～１０、比較例１～９］
　懸濁重合用分散剤として用いたＰＶＡの種類を表３に記載の通り変更したこと以外は、実施例１と同様にして塩化ビニルの懸濁重合を行った。結果を表３に示す。 [Examples 2 to 10, Comparative Examples 1 to 9]
Suspension polymerization of vinyl chloride was carried out in the same manner as in Example 1 except that the type of PVA used as the dispersant for suspension polymerization was changed as shown in Table 3. The results are shown in Table 3.
Figure JPOXMLDOC01-appb-T000006
Figure JPOXMLDOC01-appb-T000006
　実施例１～１０の懸濁重合用分散剤（ＰＶＡ－１～１０）を用いた場合、いずれも得られた塩化ビニル粒子の平均粒子径が小さく且つ、粗大粒子が少なく、良好な重合安定性を有していた。また、得られた塩化ビニル粒子は、いずれも良好な可塑剤吸収性を有するものであった。
　なお、実施例の中でも、加熱処理したＰＶＡ－９を用いた実施例９の可塑剤吸収性はそれほど高くないが、分散剤の使用量を低減することで可塑剤吸収性を改善できる。ＰＶＡ－９の重合安定性は極めて高いため、使用量を低減しても平均粒子径を十分に小さく保つことができる。また、ＰＶＡに対する加熱処理の有無のみ異なる実施例１と実施例９とを比較すると、加熱処理したＰＶＡ－９を用いた実施例９は、重合安定性が顕著に向上していることがわかる。一方、同様にＰＶＡに対する加熱処理の有無のみ異なる比較例７と比較例８とを比較すると、加熱処理により改善効果は小さい。式（１）で表される構造を有し且つ式（２）を満たすＰＶＡに対して加熱処理をすることで、重合安定性が顕著に向上することが示唆される。
　また、実施例の中でも、［Ｘ］×１０２／［Ｒａ，１］２（変性率とＨＳＰ距離とのパラメータＡ）及び［Ｘ］×１０５／［Ｒａ，２］２（変性率とＨＳＰ距離とのパラメータＢ）が比較的小さいＰＶＡ－１０を用いた実施例１０は、重合安定性がやや低い結果となった。これらのパラメータが適切に調整されたＰＶＡを用いることで、重合安定性がより高まることがわかる。 When the suspension polymerization dispersants (PVA-1 to 10) of Examples 1 to 10 were used, the average particle size of the obtained vinyl chloride particles was small, the number of coarse particles was small, and the polymerization stability was good. Had. In addition, all of the obtained vinyl chloride particles had good plasticizer absorbability.
Among the examples, the plasticizer absorbability of Example 9 using the heat-treated PVA-9 is not so high, but the plasticizer absorbability can be improved by reducing the amount of the dispersant used. Since the polymerization stability of PVA-9 is extremely high, the average particle size can be kept sufficiently small even if the amount used is reduced. Further, when comparing Example 1 and Example 9 which differ only in the presence or absence of heat treatment for PVA, it can be seen that the polymerization stability of Example 9 using the heat-treated PVA-9 is remarkably improved. On the other hand, when Comparative Example 7 and Comparative Example 8 are similarly different only in the presence or absence of heat treatment for PVA, the improvement effect by the heat treatment is small. It is suggested that the polymerization stability is remarkably improved by heat-treating PVA having the structure represented by the formula (1) and satisfying the formula (2).
Further, among the examples, [X] × 10 2 / [R a, 1 ] 2 (parameter A of the modification rate and the HSP distance) and [X] × 10 5 / [R a, 2 ] 2 (denaturation rate). In Example 10 using PVA-10 having a relatively small parameter B) between and HSP distance, the result was that the polymerization stability was slightly low. It can be seen that the polymerization stability is further enhanced by using PVA in which these parameters are appropriately adjusted.
　一方、比較例１～５、７～９においては、得られた塩化ビニル重合体粒子の平均粒子径が大きいものとなった。これは、用いたＰＶＡ－１１～ＰＶＡ－１５、ＰＶＡ－１７及びＰＶＡ－１８においては、変性率とＨＳＰ距離とのパラメータＡの値が０．４未満であるため、ＰＶＡの変性部位と塩化ビニルモノマーとの相溶性が低く、塩化ビニルモノマーと水の界面に存在するＰＶＡ量が少なくなったことによると推測される。また、ＰＶＡ－１９は式（１）中のＲの炭素数が３であり、疎水性が低いために、ＰＶＡの変性部位と塩化ビニルモノマーとの相溶性が低く、塩化ビニルモノマーと水の界面に存在するＰＶＡ量が少なくなったことによると推測される。さらに、非変性のＰＶＡ－１６を分散剤として用いた比較例６では、塩化ビニルがブロック化して重合を行うことができなかったために、塩化ビニル重合体粒子を得ることはできなかった。 On the other hand, in Comparative Examples 1 to 5 and 7 to 9, the average particle size of the obtained vinyl chloride polymer particles was large. This is because in the PVA-11 to PVA-15, PVA-17 and PVA-18 used, the value of the parameter A of the modification rate and the HSP distance is less than 0.4, so that the modification site of PVA and vinyl chloride are used. It is presumed that the compatibility with the monomer is low and the amount of PVA present at the interface between the vinyl chloride monomer and water is small. Further, since PVA-19 has 3 carbon atoms of R in the formula (1) and has low hydrophobicity, the compatibility between the modified site of PVA and the vinyl chloride monomer is low, and the interface between the vinyl chloride monomer and water is low. It is presumed that the amount of PVA present in is reduced. Further, in Comparative Example 6 in which the non-modified PVA-16 was used as a dispersant, vinyl chloride polymer particles could not be obtained because the vinyl chloride was blocked and could not be polymerized.
　本発明の懸濁重合用分散剤は、ビニル系化合物の懸濁重合の際の分散剤等に用いることができる。 The dispersant for suspension polymerization of the present invention can be used as a dispersant or the like during suspension polymerization of vinyl compounds.

Claims (5)

  1. 　下記式（１）で表される構造を有し、下記式（２）を満たすビニルアルコール系重合体を含有する、懸濁重合用分散剤。
    Figure JPOXMLDOC01-appb-C000001
     　０．４≦［Ｘ］×１０２／［Ｒａ，１］２≦３．０　　　（２）
    　前記式（１）中、Ｒは炭素数４以上の炭化水素基である。
    　前記式（２）中、［Ｘ］は前記ビニルアルコール系重合体の全構造単位に対する前記式（１）で表される構造の含有率（モル％）であり、［Ｒａ，１］は前記式（１）で表される構造と塩化ビニルとのＨＳＰ距離（（Ｊ／ｃｍ３）１／２）である。     A dispersant for suspension polymerization having a structure represented by the following formula (1) and containing a vinyl alcohol-based polymer satisfying the following formula (2).
    Figure JPOXMLDOC01-appb-C000001
     0.4 ≤ [X] x 10 2 / [ Ra, 1 ] 2 ≤ 3.0 (2)
    In the formula (1), R is a hydrocarbon group having 4 or more carbon atoms.
    In the formula (2), [X] is the content (mol%) of the structure represented by the formula (1) with respect to all the structural units of the vinyl alcohol polymer, and [ Ra, 1 ] is the above. It is the HSP distance ((J / cm 3 ) 1/2 ) between the structure represented by the formula (1) and vinyl chloride.
  2. 　前記ビニルアルコール系重合体のけん化度が６０モル％以上９９．５モル％以下である、請求項１に記載の懸濁重合用分散剤。 The dispersant for suspension polymerization according to claim 1, wherein the vinyl alcohol-based polymer has a saponification degree of 60 mol% or more and 99.5 mol% or less.
  3. 　前記ビニルアルコール系重合体の粘度平均重合度が１５０以上５，０００以下である、請求項１又は２に記載の懸濁重合用分散剤。 The dispersant for suspension polymerization according to claim 1 or 2, wherein the vinyl alcohol-based polymer has a viscosity average degree of polymerization of 150 or more and 5,000 or less.
  4. 　前記ビニルアルコール系重合体が下記式（３）を満たす、請求項１～３のいずれかに記載の懸濁重合用分散剤。
    　３．５≦［Ｘ］×１０５／［Ｒａ，２］２≦２５　　　（３）
    　前記式（３）中、［Ｘ］の定義は前記式（２）と同じであり、［Ｒａ，２］は前記式（１）で表される構造と水とのＨＳＰ距離（（Ｊ／ｃｍ３）１／２）である。     The dispersant for suspension polymerization according to any one of claims 1 to 3, wherein the vinyl alcohol-based polymer satisfies the following formula (3).
    3.5 ≤ [X] x 10 5 / [ Ra, 2 ] 2 ≤ 25 (3)
    In the formula (3), the definition of [X] is the same as that of the formula (2), and [ Ra, 2 ] is the HSP distance between the structure represented by the formula (1) and water ((J / J /). cm 3 ) 1/2 ).
  5. 　請求項１～４のいずれかに記載の懸濁重合用分散剤の存在下で、ビニル系化合物の懸濁重合を行う工程を備える、ビニル系重合体の製造方法。

          A method for producing a vinyl-based polymer, comprising a step of performing suspension polymerization of a vinyl-based compound in the presence of the dispersant for suspension polymerization according to any one of claims 1 to 4.
PCT/JP2021/039941 2020-11-04 2021-10-29 Dispersant for suspension polymerization and method for producing vinyl-based polymer WO2022097572A1 (en)

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JP2004250695A (en) * 2003-01-30 2004-09-09 Nippon Synthetic Chem Ind Co Ltd:The Polyvinyl alcohol-based dispersant having conjugated double bond in molecule
WO2015119144A1 (en) * 2014-02-05 2015-08-13 株式会社クラレ Dispersing agent for suspension polymerization of vinyl compound
CN105218713A (en) * 2014-05-27 2016-01-06 中国石油化工集团公司 A kind of polyvinyl alcohol and its production and use
WO2018083968A1 (en) * 2016-11-02 2018-05-11 日本酢ビ・ポバール株式会社 Dispersion aid for suspension polymerization, and process for producing vinyl-based polymer using same
WO2018096937A1 (en) * 2016-11-24 2018-05-31 デンカ株式会社 Modified vinyl alcohol polymer and production method therefor
WO2019156006A1 (en) * 2018-02-08 2019-08-15 デンカ株式会社 Modified vinyl alcohol polymer and dispersion stabilizer for suspension polymerization

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* Cited by examiner, † Cited by third party
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JP2004250695A (en) * 2003-01-30 2004-09-09 Nippon Synthetic Chem Ind Co Ltd:The Polyvinyl alcohol-based dispersant having conjugated double bond in molecule
WO2015119144A1 (en) * 2014-02-05 2015-08-13 株式会社クラレ Dispersing agent for suspension polymerization of vinyl compound
CN105218713A (en) * 2014-05-27 2016-01-06 中国石油化工集团公司 A kind of polyvinyl alcohol and its production and use
WO2018083968A1 (en) * 2016-11-02 2018-05-11 日本酢ビ・ポバール株式会社 Dispersion aid for suspension polymerization, and process for producing vinyl-based polymer using same
WO2018096937A1 (en) * 2016-11-24 2018-05-31 デンカ株式会社 Modified vinyl alcohol polymer and production method therefor
WO2019156006A1 (en) * 2018-02-08 2019-08-15 デンカ株式会社 Modified vinyl alcohol polymer and dispersion stabilizer for suspension polymerization

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